Mahmoud Ahmadinejad may hate the United States but the Iranian President showed himself a master of the black arts of American-style electioneering last night.

In a televised debate with his strongest challenger in the June 12 election, he savaged Mir-Hossein Mousavi, the former Prime Minister, who is seen as a "reformist".

Armed with sheaves of documents, Mr Ahmadinejad carried the battle to his opponent, dredging up his sometimes unedifying record as Prime Minister in the 1980s, repeatedly linking him to Hashemi Rafsanjani, the former President who symbolises the corrupt elite.

Mr Ahmadinejad even challenged the academic qualifications of his opponent’s wife, Zahra Rahnavard, who is campaigning for her husband.

Mr Mousavi landed some blows. In angry exchanges he characterised Mr Ahmadinejad’s foreign policy as “adventurism, instability, exhibitionism and extremism”. He said that the President had “undermined the dignity of our nation” and left Iran friendless in the region. He accused the President of turning Iran into a “mini-dictatorship”. He said that he was running for president because Mr Ahmadinejad was endangering the country.

Mr Ahmadinejad was better prepared — and shameless. Mr Mousavi said that the President had humiliated Iran by first threatening to execute the 15 British sailors captured in the Shatt al-Arab waterway in 2007, then releasing them like dignitaries. Mr Ahmadinejad retorted that he had secured an apology from Tony Blair and divided the British people from their Government.

Mr Mousavi said that Mr Ahmadinejad had undermined his country and played into Israel’s hands by repeatedly denying the Holocaust. Mr Ahmadinejad, populist to the core, said that his views on the Holocaust were backed by the Supreme Leader, Ayatollah Ali Khamenei, and by the Iranian people. He asked why Iranians should wait for the West to attack their country’s human rights record when it was suffocating the rights of Palestinians.

Mr Ahmadinejad boasted of Iran’s nuclear progress, saying that it now had 7,000 centrifuges in operation to enrich uranium. Instead of surrendering to Western pressure, like previous governments, he had defied it. After 27 years of trying to topple the Iranian Establishment, the US and Europe were now seeking talks, he said. Iran had won back the world’s respect.

“Which foreign policy has been more successful? Which brought humiliation for this country?” he asked. The great powers had prevailed on the United Nations to pass resolutions against Iran and to impose sanctions, but to no effect.

The 90-minute encounter barely touched on the economy, Mr Ahmadinejad’s greatest weakness, but when it did he recalled that under Mr Rafsanjani in the 1990s inflation reached 49 per cent — nearly double today’s rate — and the national debt was spiralling out of control. The people faced hardships, he admitted, but these were not all created in the past four years. It was not the case, he told Mr Mousavi, that “you and your friends delivered heaven and utopia and I turned it to hell”.

For Mr Mousavi, who appeared to be gaining momentum before last night, the debate was a priceless opportunity to win airtime on a state-controlled media biased heavily towards the President. How the tens of millions of Iranian viewers will judge the outcome remains to be seen. Mr Ahmadinejad appeared to land the most punches but some Iranians thought that his attacks on Mr Mousavi’s wife went too far and in Mr Rafsanjani he has made a very powerful enemy.

The debate last night was the second of six. Mr Ahmadinejad will take on Mehdi Karoubi, the former parliamentary Speaker and a reformist, on Saturday night, and Mohsen Rezai, the hardline former commander of the Revolutionary Guards, next week.

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