Iran said on Thursday that it hoped weekend talks aimed at defusing the long-running standoff over its nuclear drive would produce "positive developments" and voiced satisfaction at US involvement.

"The presence of an American delegate in Geneva will help the United States be informed directly," Foreign Minister Manouchehr Mottaki said during a visit to Syria, Iran's closest regional ally.

"We hope that the meeting in Geneva on Saturday will produce positive developments on the ground," he said at a news conference with Syrian Foreign Minister Walid Muallem.

In a major policy shift by Washington, US Under Secretary of State William Burns will attend the talks between Iranian chief nuclear negotiator Said Jalili and EU foreign policy chief Javier Solana to discuss a package of incentives offered by world powers to Tehran.

It will be the first time that Washington, which severed relations with Iran in 1980 after the Islamic revolution, has participated directly in the negotiations aimed at persuading Tehran to freeze uranium enrichment.

Western countries suspect that Iran is secretly trying to develop the atomic bomb and the United Nations has slapped several sets of sanctions on Tehran over its refusal to halt enrichment.

Iran vehemently denies seeking nuclear weapons, insisting that its programme is designed to provide energy for its growing population for the time when its reserves of fossil fuels run out.

US Secretary of State Condoleezza Rice said the United States is "firmly behind" the diplomatic efforts but did not know if Tehran would respond positively to the incentives plan proposed last month by United States and five other international partners.

"The point we are making is that the United States is firmly behind this diplomacy. Hopefully the Iranians will take that message."

Asked if she expected Tehran to respond positively to the package, she replied: "I don't know."

Mottaki also said it was examining a reported US plan for a diplomatic presence in Tehran, which would be the first such link in nearly 30 years.

"The request of the United States has been made via the media in a non-official fashion. The opening of an American interests office is the object of a study and an examination," he said.

Britian's The Guardian newspaper said Washington would announce plans next month to establish an interests section staffed with diplomats, similar to its outpost in Cuba.

Mottaki's visit to Damascus follows a trip by Syrian President Bashar al-Assad to Paris last week when French President Nicolas Sarkozy asked Syria to persuade Iran to show proof it was not seeking nuclear weapons.

Assad said then that Tehran had "no intention" of equipping itself with nuclear arms.

"The role of Syria in relation to Iran is to explain that Iranian intentions are peaceful. That is what our Iranian brothers have confirmed to us," Muallem said.