Facebook Inc. Tuesday suggested the company was worth $10 billion US, based on an investor's willingness to buy a two per cent equity stake for $200 million.

The buyer is Digital Sky Technologies, which calls itself "the largest internet investor in the Russian-speaking and Eastern European markets."

The announcement and valuation come as Facebook is dickering with investors to raise more capital, U.S. financial reports said. The reports said the company and potential investors are far apart on Facebook's value.

Facebook is privately held, so there is no public market to price its stock.

The Russian company bought preferred stock, "representing a 1.96 per cent equity stake," the companies said in a news release.

Setting a value on Facebook value has been an ongoing issue. While an investment made in 2007 by Microsoft Corp. implied the company was worth $15 billion, an internal Facebook evaluation last year concluded it was worth $3.7 billion.

Digital Sky is also planning to buy at least $100 million of Facebook common stock from existing owners, enabling them to convert their holdings into cash, the companies said.

It will not be represented on Facebook's board.

Digital Sky has offices in London and Moscow.