Facebook has raised $500 million from Goldman Sachs and Russian investment firm Digital Sky Technologies, in a deal that values the world's No.1 Internet social networking company at $50 billion, according to a person familiar with the matter.

The firms also plan to raise at least $1 billion in additional funding for Facebook, the person said speaking on condition of anonymity.

The investment gives Facebook a richer valuation than established Internet giants such as Yahoo Inc and eBay Inc and raises questions about when Facebook might pursue an initial public offering.

Facebook and Goldman Sachs declined to comment on the deal. Digital Sky Technologies could not be reached for comment.

The investment round, which was first reported by the New York Times, comes about a year and a half after Facebook raised $200 million from DST, at a valuation of $10 billion.

Goldman is planning to create a special purpose vehicle to allow its high-net worth clients to invest in Facebook, the paper reported.

It has the right to sell a part of its stake, up to $75 million, to Digital Sky Technologies, the paper said.

Facebook board member Peter Thiel told Reuters in September that Facebook would not likely undertake an IPO until sometime after late 2012. – Reuters