By Ian MacWilliam
BBC News, Almaty
An opposition group in Uzbekistan says its leader, who was arrested at the weekend, has been charged with stealing a large sum of money.
Mr Umarov believes free market reforms are essential
Members of Sunshine Uzbekistan say they still do not know the exact whereabouts of their leader, Sanjar Umarov.
The group, which is calling for free market reforms in the authoritarian Central Asian republic, says the charges have been fabricated.
Sanjar Umarov was arrested late on Saturday night.
The offices of the opposition group had been searched on Saturday by dozens of men in plain clothes, and a large number of documents were taken away.
Two other members of the group have also been arrested.
The state prosecutor's office told Sunshine Uzbekistan officials that Mr Umarov had been arrested by the police.
But as usually happens in Uzbekistan, police officials said they did not know where he was.
The prosecutor's office said Mr Umarov had been charged with stealing an undisclosed sum of money through his business dealings.
But Sunshine Uzbekistan officials said Mr Umarov no longer had any business interests in Uzbekistan.
He has family and business contacts in America, and he had recently returned from visits to the United States and Russia seeking support for his group's reform proposals for Uzbekistan.
Last week Mr Umarov wrote an open letter to the Uzbek parliament calling on deputies to begin talks with the opposition - if necessary, over the head of the increasingly unpopular hard-line president, Islam Karimov.
The letter said people no longer believed the government, which was engaged in what it called a hysterical search for enemies.
Sunshine Uzbekistan says that free market reforms are essential to kick-start the country's stagnating economy and to overcome deepening poverty.
But President Karimov's government has banned most opposition parties and rarely tolerates public criticism.