Iran executed in public on Saturday three men convicted of involvement in a bomb attack on a mosque that killed 25 people, the official IRNA news agency reported.

The bombing in a crowded Shi'ite mosque on Thursday evening wounded more than 120 people in the southeastern city of Zahedan, two weeks before a presidential election in the Islamic Republic.

'Three people convicted of being involved in the recent terrorist bombing in Zahedan were hanged in public on Saturday morning,' IRNA said, adding that the executions took place near the mosque where the bombing took place.

A Sunni opposition group named Jundollah (God's Soldiers), which Iran says is part of the Islamist al Qaeda network and backed by the United States, said it was behind the bombing, Saudi-owned Al Arabiya television said on Friday.

Ebrahim Hamidi, a local judiciary official, said the men were convicted after going through the normal judiciary process, adding that they were also involved in past 'terrorist activities'.

'The bombing happened with the explosives these three convicted criminals brought to the country,' Hamidi said.

'They were convicted as 'mohareb' (one who wages war against God), 'corrupt on the earth' and acting against national security,' he said.

It was not possible to verify the claim of Jundollah, which says it fights for the rights of Iran's minority Sunnis.

Thursday's bombing was deadliest such incident in Iran since its 1980-88 war with Iraq. A blast in a mosque in the southern city of Shiraz killed 14 people in April last year but the country has otherwise been relatively peaceful.

Iran has in the past accused the United States of supporting Sunni rebels operating on its border with Pakistan. Tehran repeated the claim on Friday, saying the 'terrorists were equipped by America'. Washington denied the allegation.

Supreme Leader Ayatollah Ali Khamenei condemned the bombing, saying 'no one can doubt that the hands of ... some interfering powers and their spying services are bloodied by the blood of the innocent.'

He called on Iranians 'to pay attention to the conspiracies of the enemies'.

Sistan-Baluchestan province, home to Iran's mostly Sunni ethnic Baluchis, is the scene of frequent clashes between security forces and heavily armed drug smugglers and bandits. – Reuters