Facebook, the world's largest social networking site, has bought FriendFeed, an up-and-coming web service, in a sign that it plans to extend its lead over rivals such as Twitter.

FriendFeed allows users to see what their friends are posting on different social media sites. The acquisition, for an undisclosed sum, is likely to boost Facebook's move into instant, real-time updates to compete with micro-blogging service Twitter.

Facebook held talks with Twitter last year with a view to buying the company but Twitter founders decided to remain independent. The micro-blogging service has gone from strength to strength with millions flocking to its stream of real-time updates on users' home pages.

Friendfeed is a messaging platform that allows friends to aggregate discussions across a plethora of media, including Twitter posts, web links, videos and images, in one place. The service has built a solid reputation in the crowded social network sector, gaining fans among early adopters and in Silicon Valley.

FriendFeed's four founders will hold senior roles on Facebook's engineering and product teams.

Facebook, which has more than 250 million registered users, said that FriendFeed would continue to operate normally as the teams determined long-term plans. All 12 employees of FriendFeed will join Facebook. The service's four founders, who worked at Google before setting up Friendfeed in 2007, will take on senior positions.

There was speculation last night that Facebook would incorporate the best features of Friendfeed into Facebook and eventually close down the original service. Facebook is positioning itself as the one place for internet users to get all their social networking updates and, for instance, could use Friendfeed's search engine to help make its stream of updates more Twitter-like.

In May, Facebook announced a $200 million investment from Russian investor Digital Sky Technologies that pegged the value of its preferred shares at $10 billion.

“Facebook and FriendFeed share a common vision of giving people tools to share and connect with their friends,” said Bret Taylor, a FriendFeed co-founder and, previously, the group product manager who launched Google Maps. “We can’t wait to join the team and bring many of the innovations we’ve developed at FriendFeed to Facebook’s 250 million users around the world.”

Paul Buchheit, another FriendFeed co-founders, said: “As we spent time with Mark and his leadership team, we were impressed by the open, creative culture they’ve built and their desire to have us contribute to it.” Mr Buchheit, the Google engineer behind Gmail and the originator of Google’s “Don’t be evil” motto, added: “It was immediately obvious to us how passionate Facebook’s engineers are about creating simple, ground-breaking ways for people to share, and we are extremely excited to join such a like-minded group.”

“Since I first tried FriendFeed, I’ve admired their team for creating such a simple and elegant service for people to share information,” Mark Zuckerberg, Facebook's founder and CEO, said. "As this shows, our culture continues to make Facebook a place where the best engineers come to build things quickly that lots of people will use."

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