The executions of the two activists from the Iranian exiled opposition group came despite a plea by the US [EPA]

Iran has carried out the first executions of activists detained in street protests after the disputed 2009 presidential poll, hanging two men it said were from an outlawed group.

The executions on Monday of the two activists from the Iranian exiled opposition group, People's Mujahedeen of Iran (PMOI) came despite a plea by US Secretary of State Hillary Clinton that they be freed.

The Tehran prosecutor's office named the executed pair as Jafar Kazemi and Mohammad Ali Hajaghaei. It did not say where they were hanged.

"Two elements of the Monafeghin (hypocrites) group were executed early today," the prosecutor's office said on its website.

The prosecutor's office said "these two hypocrites were members of an active network of the said group and were involved in the (post-election) riots under the guidance of their ringleader in England."

Hillary Clinton, the US Secretary of State, had urged the Iranian authorities to release the two activists, despite the PMOI being on Washington's list of foreign terrorist organisations.

"We are also concerned about the fate of Iranians who are in danger of imminent execution for exercising their right to free expression after the June 2009 elections," Clinton said on August 10 in a statement, naming Kazemi and Hajaghaei.

Amnesty International said it was "appalled by the executions", in a statement from Malcolm Smart, the rights group's director for the Middle East and North Africa.

Iran has sentenced around a dozen activists to death for their role in the post-poll unrest.

Six of the sentences have been upheld, according to Tehran prosecutor Abbas Jafar Dolatabadi, with the hangings on Monday reportedly the first to be carried out.

The 2009 presidential election result triggered widespread anti-government demonstrations in Tehran.

Dozens of protesters were killed, scores wounded and thousands jailed when security forces clashed with them after the announcement of the election result, which Ahmadinejad's rivals claim was rigged in his favour.