Political directors from the foreign ministries of the United States, Britain, France, Germany and Russia, as well as a senior Chinese official — the grouping known as the P5 plus one — met in Washington.
"This is really a discussion intended to talk about where the various parties in the P5+1 are, regarding timing and substance of a next Security Council sanctions resolution against Iran," said State Department spokesman Sean McCormack.
The White House warned Iran Monday that Tehran faces possible new sanctions over its suspect nuclear program, but allowed that US-Russia tensions worsened by Moscow's attacks on Georgia made seeking new UN action "slightly more complicated."
The warning followed a new report by the International Atomic Energy Agency (IAEA), the UN's atomic watchdog, that said Iran had not frozen uranium enrichment activities as instructed by the UN.
Three sets of UN sanctions have now been slapped on Iran, for defying Security Council resolutions to stop uranium enrichment, which can be a key step towards making nuclear weapons.
A previous resolution adopted in March gave the Islamic Republic 60 days to comply with the UN injunctions.
In its restricted report, the IAEA complained it was making little headway in investigating allegations that Tehran had, in the past, been involved in studies to make a nuclear warhead.
The agency "regrettably has not been able to make any substantive progress on the alleged studies and other associated key remaining issues which remain of serious concern," said the report.
"On this particular issue, we've arrived at a gridlock," a senior official close to the IAEA said, speaking on condition of anonymity.
The "alleged studies" suggest Iran may have been trying to develop a nuclear warhead, convert uranium and test high explosives and a missile re-entry vehicle.
While Western countries, led by the United States, have favored imposing more UN sanctions, Russia and China have been more reticent.
Germany has also reacted coolly to the idea, pointing to ongoing efforts by the European Union to resolve the crisis.
"Should there be no progress on the negotiations track, the German government believes the UN Security Council will become more relevant again and discussions will have to be held whether there should be new resolutions," said German foreign ministry spokesman Jens Ploetner on Friday.
"A substantial offer from the EU is on the table. We are still in talks with Iran to receive a concrete and we hope positive response to this offer. This has until now still been lacking," he said.
In a sign of the tensions with Moscow, the diplomats from Britain, France, Germany and the United States met separately early Friday at the State Department before joining their Russian and Chinese colleagues.
They were also due to discuss the situation in Georgia as well as Kosovo, McCormack said.
But he warned against "any expectations of any breakthroughs or outcomes," adding "I think it's an initial discussion."
He stressed the diplomats did not plan to issue a joint statement at the end of the talks here, which are due to prepare the ground for a ministerial-level meeting on the sidelines of next week's UN General Assembly.
US Secretary of State Condoleezza Rice was to have lunch Friday with the EU's foreign policy chief Javier Solana, who has acted as a go-between in the P5+1 discussions.
Rice has remained vague about the prospects of any breakthrough in Washington, pointing to the upcoming round of talks at the UN headquarters in New York.
