Gulnora Karimova has a lot going for her.

Prodigiously rich, tall with striking looks, a black belt in martial arts and a degree from Harvard Business School, Ms Karimova has one other invaluable attribute: she is the elder daughter of Islam Karimov, president of Uzbekistan.

At 31, she is considered one of the most powerful business people in the strategically pivotal ex-Soviet central Asian republic that neighbours Afghanistan. But the origins of her wealth and extent of her influence have remained shrouded in speculation.

Her father is a key ally in George W. Bush's war on terror, but the US has a warrant out for her arrest

Now the Financial Times has uncovered evidence that Ms Karimova has over the past two years acquired a business empire far more substantial than previously known. It includes key stakes in the country's largest mobile telephone provider and a big cement factory, as well as property and trading activities.

The investigation provides the first real glimpse into the inner workings of one of the ruling clans that came to power across central Asia following the break-up of the Soviet Union. It also raises uncomfortable questions about the nature of some of her deals and about western, especially US, support for the Uzbek ruling family.

Mr Karimov, who has dominated Uzbekistan since it became independent in 1991, is believed to be seriously ill. According to Martha Brill Olcott, a central Asia expert with the Carnegie Foundation, the expansion of Ms Karimova's business empire could be viewed as an attempt to smooth the family's exit as her father departs the political scene. Or it could be a means of holding on to power.

If the intention is to create a Karimov dynasty, says Ms Olcott, this would be "potentially very disturbing", as the possibility of instability in the country of 25m people could be high.

In spite of resources including gold and oil, the country is one of the poorest in the former Soviet Union. Most Uzbeks get by on less than $30 (€27, £19) a month while doctors and teachers make as little as $10.

Ms Karimova's upbringing was comfortable rather than opulent. Though her father held a series of high posts in Soviet-era Uzbekistan, including finance minister and head of the state planning commission, he rose to the republic's top job only in 1989.

Uzbekistan is one of the poorest countries in the former Soviet Union

At her 19th birthday party in July 1991 she met Mansur Maqsudi, scion of a prominent Uzbek-Afghan family that resides in New Jersey. They married that November, a month before her father was elected president of independent Uzbekistan.

Twelve years on, the marriage is over and a custody battle over her two children with her now ex-husband, a US citizen, means she is unable to travel to most western countries.

A US court has issued an arrest warrant against her for defying a court order to return her two children. Ms Karimova was awarded custody of the children by an Uzbek judge, but Mr Maqsudi sued in a New Jersey court and this year won his own claim. Last month the New Jersey judge issued the warrant for Ms Karimova for non-compliance with its decision. Ms Karimova risks detention and loss of her children if she travels to any country enforcing deportation agreements with the US.

That a US court has called for the arrest of the eldest daughter of one of Washington's closest allies has caused much embarrassment between the two countries. But officials on both sides say relations are strong enough to override such setbacks. The Uzbeks, US officials say, are discreet enough not to mention the matter in their discussions.

For their part, the Uzbek authorities say they have extensive documentation proving illegal activities by the Maqsudis. The family, which ran Roz Trading, an import-export business, allegedly failed to pay some $12m in taxes as well as committing other economic crimes. Mr Maqsudi denies the accusations.

In August 2001, shortly after Mr Maqsudi announced he wanted a divorce, authorities descended on the offices of Coca-Cola Bottlers Uzbekistan, in which the family had a 55 per cent stake. The Uzbek government subsequently liquidated Roz Trading's interest to pay the back taxes, and arrested or expelled members of the Maqsudi family.

After the marital break-up Ms Karimova recruited as a top aide Farhod Inogambayev, who was working for Mr Maqsudi in the United Arab Emirates but was summoned to Tashkent by the president's daughter.

Western diplomats are concerned about Ms Karimova's business empire

Soon afterwards, Mr Inogambayev and Ms Karimova travelled to the UAE and in November 2001 set up Revi Holdings in the Sharjah free trade zone, which would act as parent company for Ms Karimova's various businesses and collect the revenues from their activities.

Registration documents and share certificates for Revi, since renamed Camfed, list Ms Karimova as owner and single stock holder. Enquiries also reveal that Ms Karimova is director of a London offshoot called Revi UK, located in New Bond Street and incorporated in October 2001.

Mr Inogambayev was established as Ms Karimova's main representative in Dubai. Soon afterwards, he says, "large amounts of funds in US dollars started arriving to the companies' accounts from Uzbekistan".

Some of the money arrived from Uzdunrobita, Uzbekistan's largest mobile telephone company. According to an internal company report, Ms Karimova acquired controlling interest of the mobile operator in two stages at the beginning of 2002. Revi Holdings received first 20 per cent from International Communications Group, a Georgia, US-based shareholder, and then 31.4 per cent from the Uzbek government.

Bekhzod Akhmedov, Uzdunrobita's general director, describes Ms Karimova's interest in the company as "just a rumour". However, Dun and Bradstreet, the independent business research group, confirms Revi's interest in the company.

Later, Uzdunrobita made a bank transfer to Revi Holdings for $330,000 for "consultation services of the contract without number on 31.07.2002", according to documents seen by the FT.

Mr Inogambayev, who has left Ms Karimova's employment, says Revi was also the final recipient of $1m from Huawei Technologies, a Chinese telecommunications company that had been engaged by Uzdunrobita to create a GSM network outside Tashkent.

As part of the contract, Huawei hired Global Communications, a Caribbean offshore company, paying it just over $1m for GSM equipment. Global, however, turned around and hired Revi, depositing the same amount into Revi's bank account.

Bank documents show the amount being passed on in November 2002, first from Huawei to Global's Citibank account in Dubai, and then to Revi Holdings. Huawei representatives declined to comment.

Most recently, Ms Karimova, through another Sharjah offshore company, United International Group (Uning), acquired at least a 44.5 per cent interest in Quvasay Cement Factory, one of the country's prime industrial assets. For that holding, documents show that on March 12 this year she paid a modest $172,853.

After Mr Inogambayev stopped working with Ms Karimova, he kept a suitcase of documents detailing her financial dealings. The former Revi general director took with him scores of Ms Karimova's bank transfers and credit card statements, which provide a glimpse of the large sums of money the president's daughter enjoys at her personal disposal.

Transactions include:

• Two transfers to her Citibank account on March 25 and April 13 2002, for $950,000 and $800,000 respectively for "consultancy fees".
• An HSBC account in Jersey receiving $362,000 on March 10 2002.
• An account established at HSBC in the name of Islam Karimov, her 10-year-old son, with a balance of $1.4m.

Ms Karimova was not available for comment, though numerous attempts were made to reach her. A spokesman for the Uzbek foreign ministry - where Ms Karimova works as adviser to Sadiq Safayev, foreign minister - likewise declined to comment, saying the ministry did not maintain information on the holdings of its employees.

Western diplomats and business people have become increasingly concerned over Ms Karimova's expanding business empire. For some, it is possible evidence that Uzbekistan is finally preparing to liberalise its Soviet-style economy. Ms Karimova, according to this version, wants to be well placed when long-standing currency restrictions are removed and western investors arrive in greater numbers.

Others, however, say she is accumulating what she can while her father is still in power. A recent law passed by the country's parliament, granting the president and his family immunity from prosecution should he step down, is also seen as suggesting his imminent departure.

To this can be added Ms Karimova's purchase of a three-storey apartment in Moscow for more than $1m. Russia is one of the few countries she can travel to without risking arrest.

The US has remained cautiously supportive of the Tashkent regime, thanking Uzbekistan regularly for its support for the war on terrorism, but at the same time drawing attention to its atrocious record on human rights.

Washington bases some 1,800 troops at an air base near the southern Uzbek city of Karshi for operations in Afghanistan. In May, a 38-year-old Karshi resident died while in police custody, apparently a victim of torture.

He was the eighth known death in official custody in the past 10 months, say human rights groups. A United Nations special rapporteur called the practice of torture in the country "systematic and widespread".

Still, for some the most striking fact is that Ms Karimova is one of the few to have prospered in post-Soviet Uzbekistan. Multilateral agencies say the country is becoming more impoverished by the day.