Social networking service Twitter delayed a planned upgrade to avoid cutting daytime service to Iranians who have been using it to coordinate protests against a disputed presidential election.

Iran's top legislative body on Tuesday ruled out annulling the disputed presidential poll that has prompted the biggest street protests since the 1979 Islamic revolution but said it was prepared for a partial recount.

Websites such as Twitter and Facebook have become a focal point for young, urban Iranians opposed to President Mahmoud Ahmadinejad, who defeated Mirhossein Mousavi in Friday's election and whose government controls the state media.

Twitter Inc said in a blog post on its site a network upgrade had been planned for Monday night in the United States, which would have cut daytime service in Iran on Tuesday.

... Our network partners at NTT America recognize the role Twitter is currently playing as an important communication tool in Iran, the blog post said. NTT America is a subsidiary of NTT Communications Corporation of Japan

The hourlong maintenance was moved to 5 p.m. EDT on Tuesday, corresponding to 1:30 a.m. on Wednesday in Iran.

Twitter is a website that allows users to post messages of 140 characters or less, known as tweets, that can be seen by other users who choose to follow them. Many users post messages from smart phones allowing information to spread rapidly.

(Editing by Bill Trott)

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