Internet media company Yahoo Inc (YHOO.O) said on Tuesday it is adding media-playing features, large file transfers, new languages and other tools to its instant messaging service.

The move comes as a growing number of rivals -- from incumbents like AOL to social network sites like News Corp's (NWSa.N) MySpace -- boost their positions in the market for instant messaging services.

Yahoo Messenger 9.0 launched as a test version and has added features similar to ones seen on social networks or media-sharing sites, including extra room to post a picture or other image next to contact names and the ability to share video or photos within a message screen.

The service is adding languages from six new markets, including the Philippines, Indonesia, Malaysia, Thailand, India and Vietnam, for a total of 25 international markets.

Users can also forward messages to their mobile phones when they are away from the computer.

"This makes it easier for people to stay connected and grow their friendships," said Sabrina Ellis, vice president of Yahoo Messenger. "We added several personalization features. We think a lot of the media-sharing will really help."

Yahoo is one of the largest instant messaging service, with about 27.7 million users in September, up 19 percent from a year earlier, according to data from tracking firm comScore. Time Warner Inc's (TWX.N) AOL reported about 30.2 million users.

(Reporting by Michele Gershberg)