The talks on Iran's disputed nuclear programme, which resumed this week after a tense 14 month break, have failed to dissipate deep distrust between world powers and Tehran, analysts and diplomats said.

But the two-day talks between Iran and the European Union with Britain, China, France, Germany, Russia and the United States, which ended on Tuesday with an agreement to meet again in Istanbul in late January, marked the beginning of a new phase of dialogue, they told AFP.

"We didn't move forward one iota, but the positive thing, relatively speaking, is that a rendezvous was arranged in Turkey; that was Iran's request before they even came to Geneva," said Mohammad-Reza Djalili, a professor at the city's Graduate Institute.

The world powers spearheaded by the EU's top diplomat Catherine Ashton had originally baulked at Tehran's request to hold talks on Monday and Tuesday in Turkey, successfully proposing the western Swiss city, their traditional meeting place, instead.

But after the two-day talks, a senior US administration official "welcomed" the fact that Iran's neighbour would host the next encounter.

"We never expected major progress from this one meeting. This is a start," he said.

Francois Nicoullaud, a former French ambassador in Tehran, underlined that "the important thing is that this first meeting did not end in complete failure."

He suggested that there were still small opportunities to build on, while a western diplomat called the talks "the beginning of a process that will demand lots of patience and determination on both sides."

Dominique Moisi of the French Institute for International Relations (IFRI) believes that the form, if not the substance, of the negotiations over the standoff has changed.

"The Iranians accepted straightaway to discuss nuclear issues and there's a feeling that maybe something has changed," he explained,

But he urged caution.

"The Iranians have decided to appear to be a little more open," he said. "It's a tactical change, not yet a strategic one."

Iranian leaders have repeated in recent days that their nuclear "rights" are "non-negotiable".

Thierry Coville, a professor at the Negocia business school in Paris, nonetheless pointed to the Iranian regime's "pragmatic" approach since the Islamic revolution.

"If it's in their interest to negotiate a deal, they'll do so," he added, while European diplomatic sources highlighted the "strong signal" sent by western soldarity over Iran.

Several analysts pointed to Washington's key role in the process, alongside what appeared to be a harder line taken by the Europeans

Last week, US Secretary of State Hillary Clinton acknowledged that Iran has "the right to a peaceful nuclear programme" but said Tehran must "fully address the world's concerns about your nuclear activities."

In Geneva, the senior US administration official stood firm on the UN Security Council's requirement for "suspension" of enrichment.

But some analysts believe Washington has hinted at possible leeway for some uranium enrichment by Iran "in the future" provided Tehran gives practical assurances, changing the equation in the standoff.

Nicoullaud welcomed a US sense of "realism, compromise."

David Albright, a former International Atomic Energy Agency inspector and founder of a US think tank, suggested that international solidarity was holding and pressure was building on Iran.

"The United States feels that time is on its side," the head of the Washington-based Institute for Science and International Security told AFP.

But he doubted that the Istanbul meeting could yield progress on Iran's nuclear programme.

"I think we're probably heading for several months of standoff," he concluded.