Tencent Holdings Ltd has acquired a Google-backed Chinese social networking company for reportedly US$60 million, the country's biggest Internet firm said Tuesday.

The acquisition marked another step for Tencent, which has leads China's online game and instant message markets, to expand into the social network sector, following its US$300 million investment in a Russian social website early this year.

Shenzhen-based Tencent said it had bought Comsenz, a Beijing-based social-networking provider, which was invested by Google, Sequoia Capital and Morningside Ventures.

At present, Comsenz has more than 1.4 million online clients through its open source platform Discuz!, it said in a statement on its website.

After the acquisition, Tencent will integrate instant message platform and service, QQ, into Comsenz's website platform, which is expected to expand its dominance in China which has more than 400 million Internet users.

"Paying customers only account for 10 percent of Tencent's active IM (instant message) users, implying ample upside," said Richard Ji, an analyst at Morgan Stanley.

Both sides declined to reveal the deal value.

But China Business News reported that it was more than US$60 million, citing a source familiar with the situation.

In April, Tencent said it would buy a 10 percent stake in Russia's Digital Sky Technologies for US$300 million in what was viewed as a major overseas expansion among domestic dot-com giants.