Former US president George W. Bush said in memoirs out Tuesday that he had ordered -- then shelved -- Pentagon plans for a possible military strike on Iran over Tehran's suspect nuclear program.

"I directed the Pentagon to study what would be necessary for a strike. Military action would always be on the table, but it would be my last resort," Bush wrote in "Decision Points."

"The goal would be to stop the bomb clock, at least temporarily," said the former president, who worried about the possible impact on Iran's fledgling pro-democracy movement.

But Bush said he shelved the plans over doubts about their effectiveness and impact in Iran and Iraq as well as a bombshell US intelligence report in November 2007 that said Tehran had no active nuclear weapons program.

The National Intelligence Estimate (NIE) "tied my hands on the military side," said the former president.

"There were many reasons I was concerned about undertaking a military strike on Iran, including its uncertain effectiveness and the serious problems it would create for Iraq's fragile young democracy," he said.

"But after the NIE, how could I possibly explain using the military to destroy the nuclear facilities of a country the intelligence community said had no active nuclear weapons program?" Bush wrote.

As president, Bush never wavered from warning that "all options are on the table" for dealing with Iran, diplomatic code for the prospects of military action.

Iran has denied Western charges that its nuclear program masks a covert drive to build an atomic arsenal, insisting it will serve to generate energy in an oil-rich country dependent on gasoline imports because of a refining gap.

Bush's memoirs appeared as the United States said Iran had formally proposed dates for new negotiations with major world powers over its nuclear program.

Washington also said it hoped to resume talks as early as this month.

Nuclear talks between Iran and the so-called P5+1 -- Britain, China, France, Russia, Germany and the United States -- have been deadlocked since October 2009 when the two sides met in Geneva.

Iran has insisted the talks be held on a package of proposals for global nuclear disarmament that it announced before negotiations broke down, but world powers insist the focus should be directly on its nuclear program.

The deadlock has already led to fresh UN and EU sanctions against Iran, which were followed by several other unilateral punitive measures by other nations, including the United States.