MOSCOW, August 3 (RIA Novosti) - Iran's supreme leader Ayatollah Ali Khamenei is expected to officially confirm on Monday Mahmoud Ahmadinejad as the winner of the country's disputed June elections.

Iranian President Ahmadinejad, 52, won a landslide victory during elections on June 12 amid opposition claims that the vote was rigged. He is set to be sworn in on Wednesday.

According to official results, Ahmadinejad won the election with more than 24 million of 40 million ballots cast. The runner-up, Mir Hossein Mousavi, claimed the reelection of the hard-line president was marred by numerous irregularities.

However, Iran's constitutional watchdog, the Guardian Council, confirmed the result of the disputed presidential election after finishing a partial recount.

Ahmadinejad's victory triggered mass protests by Mousavi's supporters. Regional media reports said over 20 people were killed and about 1,000 arrested in post-election violence, Iran's most severe unrest since the 1979 Islamic Revolution.

Iranian authorities have agreed to release around 140 prisoners detained in the riots, but according to the media, some 200 people, including 50 opposition activists, still remain in jail and will face trial.

The protestors are accused of vandalizing public and private property, illegally possessing weapons including grenades, recruiting killers, attacking police, and providing video material and images to "enemy media," the state-run IRNA news agency said.