Tuesday at the D9 conference organized by the blog AllThingsD, Google Executive Chairman Eric Schmidt told that the company tried unsuccessfully to team up with Facebook in a move to tap into the new market.

Schmidt noted that social networking site Facebook had rebuffed its entreaties to do a deal, while acknowledging he had not pushed hard enough to address the rising threat posed by Facebook during his tenure as CEO.

"Three years ago I wrote memos talking about this general problem. I knew that I had to do something and I failed to do it," Schmidt said.

"A CEO should take responsibility," he said. "I screwed up."

In April this year Schmidt resigned from the post of a CEO of Google he had occupied for 10 years and handed the reign of the company to Larry Page.

Last year Google generated $29 billion in gross revenue but its core advertising business is under threat from rapidly growing upstarts such as Facebook and Groupon, while the emergence of new computing gadgets has spurred a growing rivalry with iPhone-maker Apple.

"We tried very hard to partner with Facebook," Schmidt said. "They were unwilling to do the deal," he added, noting that Facebook had traditionally partnered with Microsoft.