Iran said Tuesday it would reject talks on its nuclear programme if it was slapped with new UN sanctions as a senior US official said he expected the measures to be adopted "very soon".

A senior Russian official said there was full agreement on a fourth sanctions resolution, hours after Iranian President Mahmoud Ahmadinejad urged Western powers to drop the sanctions in favour of a nuclear fuel swap deal brokered by Brazil and Turkey last month.

"I have said that the US government and its allies are mistaken if they think they can brandish the stick of resolution and then sit down to talk with us, such a thing will not happen," Ahmadinejad told a news conference here.

"We will talk to everyone if there is respect and fairness but if someone wants to talk to us rudely and in a domineering manner the response is known already," added the Iranian leader, who is in Turkey for the summit of an Asian security grouping.

A Turkish diplomat told AFP on condition of anonymity that Ankara was trying to persuade Iran not to abandon talks if sanctions were imposed.

In Moscow, a high-ranking Russian official said the latest sanctions had been fully agreed and no problem remained for their adoption, which US Defence Secretary Robert Gates said would happen "very soon".

"I'm optimistic a resolution will be passed very soon," Gates told a press conference in London.

The UN Security Council was to hold new closed-door consultations Tuesday on the new sanctions after its 15 members failed to reach a consensus on a meeting on Monday.

The council's five permanent members -- Britain, France, China, Russia and the United States -- are co-sponsoring the sanctions draft and believe they have the votes to secure its passage.

Speaking in Istanbul, Russian Prime Minister Vladimir Putin said the new sanctions should not be extreme.

"Our point of view is that these decisions should not be excessive and should not put the Iranian people in a complicated position which would put up barriers on the path to peaceful nuclear energy," Putin was quoted by Russia's ITAR-TASS as saying.

He also added that there was "a need to settle a dangerous situation like Iran's nuclear programme by way of constructive talks with the involvement of all interested parties."

Russia, which along with China has traditionally acted to soften tough Western sanctions against Iran, has in the last months spoken of its increasing frustration with the Islamic Republic.

Ahmadinejad cautioned Russia anew on Tuesday not to "side with our enemies."

"We are neighbours with Russia. We should be friends and partners," the Iranian leader said. "There is no big problem, only a warning: do not side with our enemies."

He also urged the West not to dismiss the Turkish-Brazilian nuclear fuel swap which he described as an opportunity that should be "put to good use". "Opportunities will not be repeated," he warned.

Under the deal, Iran agreed to ship 1,200 kilograms (2,640 pounds) of its low-enriched uranium to Turkey in return for high-enriched uranium fuel for a Tehran reactor.

The United States and other world powers have given a cool reaction to the deal, saying it did not go far enough to allay fears that Tehran is using its nuclear drive as a cover for a nuclear weapons programme.

Brazil and Turkey, non-permenant Security Council members, have said they will not support the new sanctions resolution, standing behind the swap deal they forged.

Lebanon has also denied backing for domestic political reasons.

The US draft sanctions resolution would expand an arms embargo and measures against Iran's banking sector and ban it from sensitive overseas activities like uranium mining and developing ballistic missiles.

It also bars the sale of battle tanks, armoured combat vehicles, large calibre artillery systems, combat aircraft, attack helicopters, warships, missiles or missile systems to Iran.

It urges all states to inspect all cargo to and from Iran in their territory, including seaports and airports and authorizes states to conduct high-sea inspections of vessels believed to be ferrying banned items from or to Iran.

burs-han/lt