Google is to buy online messaging firm Meebo, a move expanding its capabilities for instant sharing of web pages using social networks.

Terms of the deal, announced last night on the Meebo company blog, were not disclosed.

But a report last month by the Dow Jones site All Things Digital said the price would be around $100m.

"We are happy to announce that Meebo has entered into an agreement to be acquired by Google," the company blog said.

''For more than seven years we've been helping publishers find deeper relationships with their users and to make their sites more social and engaging. Together with Google, we're super jazzed to roll up our sleeves and get cracking on even bigger and better ways to help users and website owners alike," it added.

Meebo, a privately held company, claims to reach almost half the US Internet population, in part with its "Meebo bar" which allows users to click to comment or share a Web page using a social network.

The Meebo bar can be customised and added to any page without modifying the programming codes of the website, according to the firm.