But the negotiations, with China backing Russia's position, promise to be lengthy and difficult. A draft resolution drawn up by Britain, France and Germany is generally supported by the United States.

"We cannot support measures, which in essence, aim at isolating Iran from the outside world, including the isolation of people who are charged with leading negotiations on the nuclear programme," Foreign Minister Sergei Lavrov said on Wednesday, according to Russian news agencies.

He was apparently referring to a travel ban in the draft UN Security Council resolution on Iran's nuclear ambitions, which the West believes are a cover for bomb-making but Tehran says are for peaceful uses.

The measure orders all countries to prevent the sale and supply of equipment, technology and financing contributing to Iran's nuclear and ballistic missile programmes. It would freeze assets of people and entities involved in these programmes and prevent them from travelling except for special events.

Friday's talks among the six powers are the first in more than a week. All but Germany, a key negotiator, are permanent Security Council members with veto power.

Russia's objections are expected to include softening the sanctions and redefining an exemption for a nuclear reactor Moscow is building for Iran, according to council members who were speaking on condition of anonymity because of the sensitivity of the talks.

The draft resolution exempts from sanctions the $800 million Bushehr reactor in southwestern Iran, expected to go into operation next year.

But it says Russia must check with a Security Council committee if it delivers material that can be used for weapons, such as a fuel cycle.

Russia has objected to including Bushehr in the resolution in the first place, saying it was a legal power plant under the 1970 nuclear Non-Proliferation Treaty.

"It has nothing to do (with the resolution) because it's a peaceful nuclear facility which we have been helping Iran to build in full conformity with the Nonproliferation Treaty," Moscow's UN Ambassador Vitaly Churkin, said last week.

According to Lavrov, the resolution should focus only on areas the International Atomic Energy Agency, the UN nuclear watchdog, has defined as serious, such as uranium enrichment, chemical processing and heavy-water reactors.

The draft is in response to an earlier Security Council resolution demanding Tehran suspend by August 31 its uranium-enrichment activities.

It was drawn up after Iran rejected UN demands that it suspend by August 31 uranium enrichment, which can be used to make material for power stations or warheads.

The European Union has offered economic and energy incentives if Iran temporarily suspends enrichment as a condition for talks on a peaceful nuclear programme.

But Iran has vowed not to be cowed by the threat of UN action. A senior official warned on Wednesday that Tehran may further scale back UN inspections if sanctions are imposed.

On Thursday, Iran's Revolutionary Guards fired missiles carrying cluster warheads to shouts of "God is greatest" at the start of 10 days of military manoeuvres.

"I think they're trying to demonstrate that they're tough," US Secretary of State Condoleezza Rice said.

"They're trying to say to the world: 'You're not going to keep us from getting a nuclear weapon.' The world has to say to them, 'Yes, we will," Rice said in a radio interview.

Meanwhile, Iran's Revolutionary Guards said yesterday they had fired three new types of land-to-sea and sea-to-sea missiles on the second day of "Great Prophet 2" military exercises in Gulf waters, state television reported.

It showed footage of missile launches and targets being hit, and said Iran has also boosted the range of these missiles, enabling them to hit potential targets anywhere in the Gulf region and in the Sea of Oman.

The new missiles had been designated Nur, Kowsar and Nasr, state television added.

"We have improved the range of our missiles which has been boosted from 120 kilometres (74 miles) to 170 kilometres (105 miles); this will bring the entire Persian Gulf from the Straits of Hormuz and most of the Sea of Oman within range," it quoted Revolutionary Guards deputy naval chief General Ali Fadavi as saying.

"In previous years, when American and British forces entered Iranian territorial waters in the northern Persian Gulf we captured them," Fadavi added.

"Today we tightly control all of the Persian Gulf and Sea of Oman region, and no movement can escape our control."