UPDATE 1-Russia's Vimpelcom under investigation over Uzbekistan

March 12 (Reuters) - Russian mobile phone operator Vimpelcom said on Wednesday it was being investigated by the U.S. Securities and Exchange Commission and Dutch authorities, probably in connection with its operations in Uzbekistan.

Former Soviet Uzbekistan has been a problematic country for foreign mobile companies to invest in. Rival Russian mobile operator MTS had all its assets confiscated in the country while Sweden's TeliaSonera has had its operations investigated by Swedish prosecutors.

Vimpelcom, in which Russia's Alfa Group and Norway's Telenor are the biggest investors, has 10.5 million subscribers in Uzbekistan, central Asia's most populous country, out of 220 million in total across Russia, Italy and various emerging markets.

Vimpelcom said it had received a letter from the U.S. SEC on March 11 stating that they were conducting an investigation related to the company and requesting documents.

The company also said its headquarters in Amsterdam was visited on March 11 by representatives of Dutch authorities including the Dutch public prosecutor office, who took documents and informed Vimpelcom it was the focus of a criminal investigation in the Netherlands.

"The investigations appear to be concerned with the company's operations in Uzbekistan. The company intends to fully cooperate with these investigations," Vimpelcom said in the statement.

Last year, Uzbekistan's tax authorities launched an investigation into Vimpelcom's mobile unit, Unitel.

That investigation followed the confiscation of all assets owned by the Uzbek subsidiary of top Russian mobile operator MTS in a criminal case against its local staff. MTS took a $1.1 billion write-off in 2012 after an Uzbek court revoked its local operating licence in a case that MTS called a "classic shakedown" of foreign investors.

Sweden's TeliaSonera has also been subject to investigations by Swedish prosecutors into the company's Uzbek business that resulted in the exit of the company's former chief executive and most of the board.

The prosecutors are looking into allegations that Telia paid around $350 million for its 3G licence to a company it knew was a front for Gulnara Karimova, the daughter of Uzbek president Islam Karimov.