Some 12.3 million consumers in the United States and Western Europe used  their mobile phones to dial up a social networking service in the three months  ending in June, according to the latest m:metrics mobile phone usage survey. That translates into roughly 10 percent growth across all regions.

The U.S leads the way with 3.5 percent of all mobile subscribers using their phones for social networking, followed by Italy with 2.8 percent. The U.K. trailed with 2.5 percent and Spain had 2.3 percent.

MySpace was by a wide margin the most popular mobile social networking tool with 3.7 million users in the U.S. and and 440,000 in the U.K. Facebook, by comparison, has 2 million mobile users in the U.S. and about 307,000 in Britain. Rounding out the top three was YouTube in the U.S., with 901,000 mobile visitors, and Bebo in the UK, with 288,000.

Facebook saw the fastest growth overall, going from fifth place in the U.K., for example, to second spot. It overtook Bebo, MSN/Windows Live and YouTube, but it was still only half as popular as MySpace.

The kinds of phones available to people influenced the services they have used, said Paul Goode, senior analyst at m:metrics. In Italy, for example, where 3G and smart phones have a higher penetration, YouTube was much more popular. This was because these phones are capable of handling much faster video upload and download times, said Mr. Goode.