Google confessed it tried unsuccessfully to team up with Facebook, as the search giant adapts to a shifting technology landscape and strives to maintain growth.

Google executive chairman Eric Schmidt told a conference 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 on Tuesday. ?A CEO should take responsibility,? he said. ?I screwed up.?

Schmidt, who ended his 10-year run as CEO in April and handed the reins to 38-year-old Google co-founder Larry Page, made the comments at the D9 conference organised by the blog AllThingsD. Page is pushing the company?s employees to develop more ways to connect people with their friends and family like Facebook already does.

Facebook?s growing popularity is becoming more nettlesome for Google. As Facebook?s audience grows, it is attracting more online advertising and stunting Google?s financial growth. Perhaps even more troubling to Google, much of the information on Facebook?s website can?t be indexed by Google?s search engine. That restriction threatens to make Google less useful as more people form social circles online and could make it more difficult to get a handle on personal preferences so it can do a better job selling ads.

Google, which generated roughly $29 billion in gross revenue last year, is the world?s No1 search engine. 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.

Schmidt did not specify what sort of deal with Facebook he had tried to secure, but noted that Google?s search could be improved with access to Facebook?s vast trove of data about Web surfers? friends and acquaintances. ?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.

Schmidt said the company has been working hard to solve this ?identity? problem. ?I think the industry as a whole would benefit from an alternative? to Facebook?s network, he said.

Google has tried to negotiate partnerships with Facebook, Schmidt said, only to be repeatedly rebuffed. He said Facebook has preferred teaming up with another Google rival, Microsoft, which owns a 1.6% stake in Facebook. Google also has ties to Facebook; one of its former executives, Sheryl Sandberg, is Facebook?s chief operating officer.

During a nearly 90-minute onstage interview, Schmidt discussed the increasingly competitive landscape, as well as the growing privacy and regulatory scrutiny it is facing. But he seemed dismissive of software giant Microsoft, which was ?not driving the consumer revolution?.

A former Apple board member, Schmidt admitted their relationship had gotten ?rough? as Google began to develop its Android smartphone operating system, though they remained partners in certain businesses.