HELSINKI, July 24 (Reuters) - Nokia , the world's top mobile phone maker, said on Tuesday it would buy U.S.-based photo-sharing social networking site Twango, but did not disclose the price.

Twango was founded in 2004 but U.S. traffic data from measurement firms Hitwise and Quantcast and global data from Alexa.com show it has found little audience so far compared to sites like YouTube, PhotoBucket or Flickr.

Nokia has increased its acquisitions under Chief Executive Olli-Pekka Kallasvuo, who took over in June 2006. He has said the firm is looking to acquire more companies to strengthen its multimedia and corporate offering.

"The Twango acquisition is a concrete step towards our Internet services vision of providing seamless access to information, entertainment, and social networks," Anssi Vanjoki, head of Nokia's multimedia unit said in a statement.

"We have the most complete suite of connected multimedia experiences including music, navigation, games, and - with the Twango acquisition - photos, videos, and a variety of document types," he said.

Analysts see Internet social networks as a key element in the future of the media business. News Corp.'s 2005 acquisition of MySpace has boosted the value of Rupert Murdoch's media conglomerate as a whole.

Additional reporting by Eric Auchard in San Francisco and Sakari Suoninen in Helsinki