Nevertheless, Iran's top nuclear negotiator, Hossein Mousavian, said that a compromise could still be reached with European negotiators to avert the risk of U.N. sanctions.

Britain, France and Germany have offered Iran a trade deal and peaceful nuclear technology - including a light-water research reactor - in return for assurances Iran would indefinitely stop enriching uranium. Uranium enriched to a low level can be used to produce nuclear fuel, but if enriched further it can be used to make nuclear weapons.

While lawmakers were discussing the bill, Mousavian ruled out an indefinite suspension of enrichment activities. But he suggested Iran would consider halting the building of more nuclear facilities, which it would need to produce enough fuel for additional power plants.

Washington has accused Iran of trying to build atomic weapons and has pushed for the case to be referred to the U.N. Security Council for possible sanctions if Tehran doesn't give up all uranium enrichment activities before a Nov. 25 meeting of the International Atomic Energy Agency, the U.N.'s nuclear watchdog.

"I see the chance of a compromise before November as 50-50," Mousavian said.

"We have rejected two possibilities: cessation and unlimited suspension," he said. "We told the Europeans if your target is cessation, it will be impossible. But we are flexible if your proposal is balanced."

Tehran maintains its nuclear program is for peaceful energy purposes.

Mousavian said some progress was "definitely" made during Iran's talks last week with Europeans, who he said "showed flexibility and understanding."

However, those negotiations could be hampered if Iran's government obliges calls by lawmakers to push ahead with enrichment.

Parliament speaker Gholam Ali Haddad Adel said Sunday's vote by the conservative-dominated parliament in favor of the outline of a bill that forces their government to resume uranium enrichment sent a message to the world.

"The message of the absolute vote for the Iranian nation is that the parliament supports national interests," he said. "And the message for the outside world is that the parliament won't give in to coercion."

No date was set for discussing details of the legislation and the outline did not include a deadline for the government to resume uranium enrichment.

Another vote is expected on the bill when details are worked out, but that is usually a formality. The bill also requires approval by the hard-line Guardian Council.

Iran is not prohibited from enriching uranium under its obligations to the Nuclear Nonproliferation Treaty, but faces growing international pressure to suspend such activities.

Britain, Germany and France have warned most European states will back Washington's call to refer Iran's case to the Security Council if it does not agree to a compromise. The IAEA is also trying to persuade Iran to limit nuclear activities.