Yahoo: Microsoft's Bing starts to power its US Internet search

* Co says completed transition to Bing

* Bing now powers Yahoo's U.S. and Canada search * More markets and languages will be included soon

Aug 25 (Reuters) - Internet firm Yahoo Inc (YHOO.O) said it has completed the transition of its U.S. and Canadian English-language search capabilities to Microsoft Corp's (MSFT.O) Bing platform.

"Yahoo web, image, and video search experiences on both desktop and mobile devices are now powered by the Microsoft platform in the U.S. and Canada, with more markets to come," Shashi Seth, senior vice president of Yahoo search products, said in a blog post.

Satya Nadella, senior vice president of Microsoft's Online Services Division, said the company is now working on the migration to adCenter -- a pay-per-click advertising platform -- and is optimistic about completing this phase later this year.

Both Bing and Yahoo lag behind market leader Google Inc (GOOG.O) in the Internet search business. They have formed a partnership to increase their combined market share to win more ad search dollars.

In July 2009, Yahoo and Microsoft signed a 10-year deal that calls for Microsoft to provide the back-end technology powering search on Yahoo's websites, in a bid to create a strong Number 2 search entity to compete with Google. (Reporting by Sakthi Prasad in Bangalore; Editing by Dhara Ranasinghe)