The United States, Russia, China, Britain, France and Germany met in Washington to help prepare for a meeting next week of US Secretary of State Condoleezza Rice and her counterparts from the other five countries, it said.

At their talks, the foreign affairs political directors of the so-called P5-plus-one -- the five permanent UN Security Council members plus Germany -- also reviewed developments from their last meeting on July 19, it said.

The six "reaffirmed their collective commitment to the dual-track strategy" of offering incentives to Iran if it cooperates or punishment if it does not, according to the Department statement.

They agreed they would "continue to encourage Iran to accept the generous offer of incentives that was presented to Iran in June."

The six "remain committed to exploring possible further measures on the second track," a department statement said.

They also discussed the concerns raised in the September 15 International Atomic Energy Agency (IAEA) report and "strongly urge Iran to cooperate fully with the IAEA's investigation," the statement said.

The IAEA, the UN's atomic watchdog, said Iran had not frozen uranium enrichment activities as instructed by the United Nations.

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."

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, State Department spokesman Sean McCormack said.

But he warned against "any expectations of any breakthroughs or outcomes," adding "I think it's an initial discussion."

Rice had 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.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.