Opera Software unveiled a new version of its mobile browser for Apple's iPhone and iPad on Tuesday.

Opera is the world's most used mobile browser ahead of Google's Android, Apple, and Nokia controlling 21.6 percent of the market in May so far, according to Web analytics firm StatCounter.

The Android, iPhone and Nokia browsers all have 16-17 percent market shares.

Opera's new browser features a share button, so users can post, tweet, or share info on Facebook, vKontakte or My Opera, the company said.

In April 2010 Apple accepted distribution of Opera's browser for its iPhone after a long review, opening a market it had closely guarded.

Opera's iPhone browser was downloaded more than 2.6 million times in 2010 April alone and was at the time the most popular application in many countries.

(Reporting by Tarmo Virki; Editing by Dan Lalor)

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