Digital Sky Technologies (DST), a leading internet-investment group and an investor in Facebook, has agreed to put in the majority of approximately $180 million investment in Zynga Game Network Inc (Zinga), the world's largest social game developer, a statement released by Zynga said. 

Other new investors in Zynga include the US hedge fund Tiger Global and venture firm Andereessen Hortwitz, in addition to Institutional Venture Partners which has increased its stake.

San Francisco-based Zynga, founded in 2007 has grown to become the largest social gaming company in the world with over 230 million monthly active users. The games are available on social networking sites such as Facebook, MySpace, Bebo, Friendster, etc, as well as Yahoo and iPhone.

Popular Zynga games include FarmVille, Mafia Wars, CafeWorld, FishVille and Zinga Poker and the recently launched PetVille. Although the games are available for free, Zinga makes money by selling virtual goods such as farm tractors or home decorations to over one million users.

According to some estimates, the company's annual revenue is over $200 million which is poised to grow to around $350 million next year.

Zynga founder and CEO Mark Pincus said: ''We are excited about our relationship with DST as they are a global player dedicated to creating services that are meaningful to consumers in the long term. The investment from DST allows us to continue delivering on the promise of social games for consumers, making fun the biggest way for people to interact.''

Yuri Milner, chief executive of DST said: ''We share in Zynga's mission of connecting people through games and believe they are in a solid position with their team, offerings and market share to succeed in a dramatic way.''

''Our earlier investment in Facebook and now in Zynga underscores our premise that social networking and social entertainment will define the next generation of the web,'' Milner added.

DST which has offices in Moscow and London is a leading global investor in proven internet business models including social networking, e-payment, online shopping, social gaming etc. Its companies hold top positions in CIS states including Russia, Ukraine, Kazakhstan, Georgia and Armenia.

Russian billionaire Alisher Usmanov holds 35 per cent stake in the venture while its founders Milner and Grigory Finger own over 40 per cent.

Earlier in May, DST invested $200 million in Facebook, the world's largest social-networking site to acquire close to 2-per cent stake through preferred stock, valuing Facebook at $10 billion. (See: Digital Sky deal values Facebook at $10 billion)

Recently, social gaming market has been attracting investor attention which is visible by last month's acquisition of game creator Playfish by Electornic Arts in a $400 million deal. (See: Electronic Arts buys Playfish for $400 million)