Making a surprise appearance at the Web 2.0 Summit in San Francisco on Thursday, Google co-founder Sergey Brin expressed his disappointment at the July-signed Internet search pact between Yahoo and Microsoft, saying that it was rather distressing to see Yahoo decrease its focus on Internet search.

Brin, however, refrained from commenting on whether or not the government regulators should approve the Yahoo-Microsoft deal.

Answering to a number of pertinent questions asked onstage by John Battelle, the chairman of the ongoing conference, Brin, who co-founded Google with Larry Page, noted that there is still healthy competition in the Internet search-advertising market despite the noticeable dominance of Google.

Saying that the Yahoo-Microsoft search outsourcing deal would essentially mean that Yahoo would turn off its back-end search crawling and indexing systems, thereby deciding to use Microsoft’s new search engine Bing to power its search engine, Brin said that the Yahoo decision to decrease its innovative efforts was extremely deplorable.

Brin said: “I think there’s a lot of interesting stuff going on. I think it’s a shame that Yahoo has abdicated that area. Yahoo had a number of interesting innovations there, and I wish they could have remained in search.”

Talking about Microsoft’s Bing search engine, Brin said that it has served as a particular reminder to Google that Internet search still remains a fairly “competitive market.”