The decision was greeted by a loud eruption of the nighttime rooftop chanting that has become a hallmark of opposition protests amid an intensifying government crackdown.

Before the announcement, security forces, including members of the pro-government Basij militia, deployed in large numbers to prevent street protests, said witnesses. Yet that did not stop people from taking to their rooftops to chant "Allahu akbar" (God is great) and other slogans in a form of protest used by the popular movement that ultimately deposed the shah of Iran three decades ago.

The council, a 12-member supervisory body that oversees elections and certifies results, made the announcement after conducting a partial recount in an effort to mollify political opponents who charge that Ahmadinejad benefited from massive vote-rigging.

In a letter to Interior Minister Sadegh Mahsouli, the head of the Guardian Council said members reached their "final decision" on the election results following an extended review, Iran's state television and radio network reported.