Having failed to win a response with an 18-page letter to President George Bush or to a request to visit the site of the September 11 2001 attack on New York, Ahmadinejad has offered himself as an observer in next year's presidential election.

The proposal came in a speech to volunteers with the Basij, a pro-regime militia. He said he was prompted by a belief that Americans would vote against the current administration in a truly free poll.

However, the terms of Ahmadinejad's offer appeared to betray some confusion about the potential candidates.

"If the White House officials allow us to be present as an observer in their presidential election we will see whether people in their country are going to vote for them again or not," he said. The US constitution prevents Bush from seeking a third consecutive term, while no member of his administration is expected to be in the running in next November's poll.

Bush and international human rights groups voiced doubts about the legitimacy of Iran's 2005 presidential election, which brought Ahmadinejad to power. More than 1,000 potential candidates were disqualified by the guardian council, a powerful body of clerics and judges.

Some domestic critics pointed out yesterday that Ahmadinejad's idea clashed with his government's opposition to allowing independent observers at Iranian elections. The interior ministry, controlled by one of the president's most hard-line allies, has rejected pressure for party representatives to be allowed to oversee proceedings at polling stations for next March's parliamentary poll.

The election is expected to provide a major test of Ahmadinejad's popularity. Leading regime figures, including two former presidents, Hashemi Rafsanjani and Mohammad Khatami, have warned against possible attempts to rig it through mass candidate disqualifications and other measures.