SAN FRANCISCO - YouTube is expanding its mobile service to include virtually all of the videos available on its website, hoping to widen its sway on pop culture.

Beginning Thursday, most people equipped with the latest generation of mobile phones will be able to peruse tens of millions of YouTube videos. YouTube first began showing videos on phones in 2006, but only a few thousand clips had been available until now.

Besides opening up its vast video library available on so-called "smart" phones, YouTube also is providing mobile access to many of the same features that have become staples of its website. The additional mobile features include the ability to rate videos and share clips with friends.

More than 100 million devices worldwide should be able to access the expanded mobile service, YouTube estimated. The handsets must have streaming capability and have a 3G operator.

YouTube, which is owned by Google Inc., is trying to make it easier for people to upload videos from their phones with a new application that can be installed on some handsets. The "YouTube for Mobile" program initially will work on limited list of devices that include some Sony Ericsson and Nokia models.

San Bruno-based YouTube has no immediate plans to make money off the mobile service but eventually may show ads to viewers, said Hunter Walk, YouTube's product manager. For now, YouTube just wants its audience to become more accustomed to watching video on their phones, Walker said.

Google bought YouTube for $1.76 billion 14 months ago as part of an effort to build a channel for video advertising.

YouTube's mobile service, reachable at http://m.youtube.com, is being offered in 16 other countries besides the United States and 10 other languages besides English. The other languages are: Japanese, Italian, French, Spanish, Dutch, Polish, Portuguese, Chinese, German and Russian.

YouTube's Web site already serves up more than 200 million video clips today, ranging from kids goofing off in their bedrooms to presidential candidates on the campaign trail.