Washington  - US President George W Bush reiterated his pledge that the United States will not allow Iran to develop nuclear weapons in a wide ranging speech on the Middle East Friday.

"For the safety of our people and the peace of the world, America will not allow Iran to develop a nuclear weapon," Bush said at the Saban Center for Middle East Policy at the Brookings Institution.

Bush suggested the US invasion of Iraq to topple Saddam Hussein prompted Iran to slow its nuclear ambitions, only to resume them after the election of President Mahmoud Ahmadinejad in 2006.

"The defeat of Saddam also appears to have changed the calculation of Iran," Bush said.

US intelligence officials in a report released in December 2007 said Iran halted its nuclear weapons programme in 2003 but was still seeking the capability to develop the weapons. Iran has continued to enrich uranium in defiance of UN Security Council resolutions.

The United States and its European partners have offered Iran diplomatic and economic incentives to suspend uranium enrichment. Iran maintains it has the right to continue and that it is merely for civilian reactors.

Bush acknowledged the war in Iraq has been longer and tougher than expected, but defended his decision to launch the March 2003 invasion that has since claimed the lives of more than 4,000 US soldiers and by some estimates as many as 100,000 Iraqis.

Bush said following the September 11, 2001 attacks, the United States could not allow Saddam to bully the region and rebuff Security Council demands to surrender weapons of mass destruction.

"In a world where terrorists armed with box cutters had just killed 3,000 people, America had to decide whether we could tolerate a sworn enemy that acted belligerently, that supported terror, and that intelligence agencies around the world believed had weapons of mass destruction," he said.

Weapons were never found, and Bush conceded in November that the failure of the intelligence community on Saddam's alleged weapons was the "biggest regret" of his presidency. (dpa)