Russian Internet-investment group, Digital Sky Technologies, (DST) has invested $200 million in the world's largest social-networking service Facebook for a 1.96-per cent stake through preferred stock.

This is the second time Facebook has raised major equity funding after Microsoft acquired a 1.6-per cent stake in Facebook for $240 million in October 2007 (See: Microsoft pips Google to acquire a stake in Facebook)  valuing the company at $15 billion.

The transaction values Facebook at $10 billion.

The valuation of Facebook at $10 billion sems high in the current global economic downturn, compared to Microsoft's $15-billion valuation of an investment of $240 million in 2007 for a 1.6-per cent stake.

The differences between the two valuations, implies a loss of valuation  of $5 billion since the earlier valuation in 2007, despite its rising user base.

Just a few months after its fifth anniversary, Facebook, last month reportedly welcomed its 200 millionth user. (See: Social networking site Facebook welcomes its 200-millionth user)

The Russian investment has come as the social-networking company had been talking to a range of venture capital and private-equity firms about raising more money to help fuel its growth.

''This investment demonstrates Facebook's ongoing success at creating a global network for people to share and connect,'' said Facebook CEO Mark Zuckerberg. ''We've worked hard to bring more than 200 million people – 70 per cent outside of the US – onto Facebook to share with friends, family and co-workers.''

''A number of firms approached us, but DST stood out because of the global perspective they bring – backed up by the impressive growth and financial achievements of their internet investments. We're looking forward to working with the DST team,'' he added.

The DST proposal is the latest in a string of funding offers Facebook has received. Under the terms of DST's two-part investment, the Russian investment group will offer to buy between $100-150 million in Facebook common stock from current or former Facebook employees at a $6.5 billion valuation.

Based in London and Moscow, DST, run by Russian investor Yuri Milner, holds significant interests in Russia and Eastern Europe, such as Mail.ru, Forticom and vKontakte.

DST's main assets account for over 70 per cent of all page views in Russian-speaking internet and its social networks are the market leaders in more than 13 countries, addressing a combined population of more than 350 million.

The controversial Russian tycoon Alisher Usmanov, the world's 450th-richest individual with a net worth estimated at $1.6 billion, according to Forbes and owner of British soccer club Arsenal, has a 32-per cent stake in Digital Sky.

Founded in February 2004, Facebook had said that its mission is to give people the power to share and make the world more open and connected. Anyone can sign up for Facebook and interact with the people they know in a trusted environment.

Facebook is a privately held company and is headquartered in Palo Alto, California.

Facebook is a social utility that connects users and  ranks as one of the top photo-sharing websites, with more than 15 billion pictures uploaded onto its service.

CEO Mark Zuckerberg had said in a blog post that it took 20,000 years for the world's population to get to 200 million people. For Facebook, it was just under 5 years. In January 2009 Facebook's community was at 150 million, and grew to 175 million in February.

(Also see: Russian firm Digital Sky to invest in Facebook: WSJ)