Microsoft's new Internet search engine Bing slightly increased its share of the US search market in February, the ninth straight month of modest gains, online tracking firm comScore said Wednesday.

Bing's share of the US search market rose to 11.5 percent in February from 11.3 percent in January, the Web analytics firm said.

Meanwhile, Microsoft's search partner Yahoo! saw its share dip to 16.8 percent in February from 17.0 percent in January, comScore said.

Google remained the overwhelming leader of the lucrative US search and advertising market last month. Its share edged up to 65.5 percent in February from 65.4 percent in January.'s share fell to 3.7 percent from 3.8 percent while AOL's was steady at 2.5 percent.

February was the ninth consecutive month of slight gains in search share for Bing, which Microsoft unveiled in June accompanied by a 100-million-dollar advertising campaign in a bid to challenge search juggernaut Google.

Microsoft and Google have been consistently upgrading online search service features in what has thus far been a lopsided duel favoring the Mountain View, California-based Internet king over the software giant.

The competitors have been focused on improving mobile search offerings and incorporating real-time content from popular online communities such as Twitter and Facebook into search results.

Yahoo! and Microsoft unveiled a 10-year Web search and advertising partnership in July that set the stage for a joint offensive against Google.

Under the agreement, Yahoo! will use Microsoft's search engine on its own sites while providing the exclusive global sales force for premium advertisers.