The diplomats, including Bruce Cleghorn, Britain's High Commissioner, left in protest at Mahathir Mohamad's broadside during a speech at the conference in Kuala Lumpur.

Mahathir, who ruled predominantly Muslim Malaysia for 22 years before retiring in 2003, also defended his human rights record in government.

He was often criticised for detaining suspects without trial under a security law and for the imprisonment of the former deputy prime minister, Anwar Ibrahim.

Mahathir decried the deaths of thousands of Iraqi civilians as a result of the U.S.-led military invasion and occupation of the country.

He compared U.S. and British actions in Iraq to rocket attacks by Israel on Palestinians, and referred to those countries as "these terrorist nations."

"The British and American bomber pilots came, unopposed, safe and cosy in their state-of-the-art aircraft, pressing buttons to drop bombs, to kill and maim," Mahathir said of the Iraq invasion.

"And these murderers, for that is what they are, would go back to celebrate 'mission accomplished'. Who are the terrorists? The people below who were bombed or the bombers? Whose rights have been snatched away?"

He also questioned why there was no tally of Iraqi deaths while every U.S. soldier's killing is documented.

"These are soldiers who must expect to be killed," Mahathir said.

"But the Iraqis who die because of the U.S. action or the civil war in Iraq that the U.S. has precipitated are innocent civilians who under the dictatorship of Saddam Hussein would be alive."

Mahathir, who when in power was a U.S. ally in the fight against terrorism, although he opposed the wars in Iraq and Afghanistan, noted that the reason for invading Iraq was that Saddam had weapons of mass destruction.

"As we all know it was a lie," he said. "Worse still, the powers which are supposed to save the Iraqi people have broken international laws on human rights by detaining Iraqis and others and torturing them at Guantanamo, Abu Ghraib and elsewhere," he said, referring to the U.S. prison camps.

Bruce Cleghorn later said he had attended the conference out of respect for Mr Mahathir as a former prime minister.

The U.S. Embassy had decided earlier not to send representatives to the event.

The U.S. accused Mahathir of human rights violations when he sacked Anwar as his deputy in 1998 and sentenced him to 15 years in prison on what many thought were trumped-up charges.

He was freed on appeal last year.

Washington largely stopped criticising Malaysia's use of a security law that allows indefinite detention without trial after it was used to lock up dozens of terrorist suspects, some with alleged links to the 11 September terror attacks.