BERLIN, (Reuters) – World powers played down prospects for a deal on new sanctions against Iran ahead of a meeting on Tuesday aimed at ratcheting up pressure on Tehran to curb its sensitive nuclear work.

The West suspects Iran is secretly pursuing an atomic bomb, but Tehran says its nuclear programme is for peaceful power generation.

U.S. Secretary of State Condoleezza Rice, arriving in Berlin for the meeting of foreign ministers from the five permanent U.N. Security Council members and Germany, said powers still had “some way to go” in agreeing a third U.N. sanctions resolution.

Host Frank-Walter Steinmeier said he hoped the meeting, which starts at 4:30 p.m. (1530 GMT), would show Iran the international community was united in its concern over the Islamic Republic’s nuclear ambitions. “I can’t promise we will come out of this meeting with an agreement on how to proceed in the U.N Security Council, that we will agree on the text of a resolution and I can’t tell you what new sanctions will look like,” German Foreign Minister Steinmeier told ARD public television. “But I am very optimistic that we can get results and show Iran that our concerns cannot be ignored, that the international community, including Russia and China, is united,” he said.

Ahead of the meeting, Iran reiterated that new international sanctions would not stop it from pursuing its “legitimate and legal rights” to a nuclear programme.

Washington has spearheaded the drive for more punitive measures and is keen to ensure a new resolution tightens the noose on more Iranian state banks.

Russia and China, both commercial partners of Iran, have hardened their opposition to tougher sanctions since a U.S. intelligence report last month said Iran had halted its nuclear weapons programme in 2003.

While both appear willing to accept a new resolution, they are seen as unlikely to accept measures that would hurt economic ties. “China hopes it can achieve a resolution that raises pressure but does not risk serious economic fallout,” said Yin Gang, an analyst at the Chinese Academy of Social Sciences.

Political directors from Britain, China, France, Germany, Russia and the United States narrowed differences in calls over the weekend, diplomats say. But Rice said there were “still some gaps to close” and suggested the Berlin meeting, which is scheduled to last just 1-1/2 hours, would focus on longer-term strategy more than detailed negotiations on a resolution.

International Atomic Energy Agency (IAEA) director Mohamed ElBaradei won agreement from Iran this month to answer questions about its past covert nuclear work within four weeks and some countries may prefer to wait before agreeing new steps.

The foreign ministers last met to discuss Iran in September in New York and have made little tangible progress since then.

China said on Tuesday that the nuclear standoff, which dates back to 2002, had reached a “critical moment”.