By Carol Giacomo

VIENNA, Jun 1 (Reuters) Iran has only weeks to decide whether to accept a US offer of multilateral talks on the nuclear issue before Washington and its major power allies push forward with sanctions, a US official said today.

As US Secretary of State Condoleezza Rice arrived in Vienna for a meeting on Iran of major power foreign ministers, US officials were optimistic that a proposal for direct US participation in talks with Iran would be accepted.

Iranian Foreign Minister Manouchehr Mottaki today said Tehran was open to talks on ''mutual concerns'' but rejected Washington's pre-condition that it stop enriching uranium, the fuel for nuclear reactors and a vital component in atomic bombs.

US officials said they did not accept Mottaki's comments as final since the carrots-and-sticks package to be worked out by the veto-wielding permanent members of the United Nations Security Council (the United States, Britain, France, China, Russia) and non-permanent member Germany at today's meeting has not been fully agreed and presented to Tehran.

One US official told Reuters that ''there was still a gap to be bridged over what specific sanctions Russia will support'' as part of the diplomatic initiative aimed at getting Iran to end nuclear activities that the West says are intended to produce weapons under the guise of a peaceful energy programme.

Meanwhile, the United States will delay pursuing a UN Security Council resolution against Iran under Chapter 7 of the UN Charter until after Tehran responds to the US talks proposal and the major power carrots-and-sticks package, US officials said.

The officials spoke anonymously because of the sensitive nature of the diplomacy.

More Reuters SI RS1656