NEW YORK: Iran and six world powers held more "useful" talks on Tehran's nuclear program, both sides said, although a Western diplomat said they were still struggling to overcome deep disagreements on the future of Iranian atomic capabilities.

Their remarks came after two days of expert-level talks in New York between Iran and the United States, France, Germany, Britain, China and Russia on a long-term accord meant to end by a deadline of July 20 a decade-old dispute over suspicions that Tehran has sought the means to develop nuclear weapons.

"(The six powers) and Iranian technical experts had a useful meeting on 6-7 May in New York," an EU spokesman said.

"The talks aimed at further deepening of the knowledge on the issues and to contribute to the preparations for the next round of (senior-level) negotiations on a comprehensive agreement due to take place next week in Vienna."

The talks were a prelude to next week's political-level negotiations in the Austrian capital Vienna.

Iranian nuclear negotiator Hamid Baeedinejad also described the New York discussions as "useful", the official IRNA news agency said on Thursday. "Parties involved in technical and expert will continue discussions to prepare for the next round of talks next week in Vienna," Baeedinejad said.

The West suspects Iran has engaged in nuclear research-and-development (R&D) work geared to yielding bombs. Iran says its nuclear program is entirely peaceful, intended solely for generating electricity and isotopes usable in cancer treatment.

Iran's priority in the negotiations is to bring about an end to biting international sanctions that have damaged its oil-dependent economy by forcing a sharp reduction in crude exports from the Islamic Republic.

A Western diplomat, who spoke to Reuters on condition of anonymity, said Iran and the six powers had made progress on scenarios for resolving a dispute over Iran's Arak nuclear reactor, which could yield significant quantities of bomb-grade plutonium if it is brought on line without major modifications.

"More difficult for getting a deal is uranium enrichment in general and centrifuge R&D," the diplomat said.

Enrichment is a problematic issue for Israel, Washington's principal ally in the Middle East. Israel insists Iran be stripped of enrichment capabilities under a potentially imminent nuclear deal, a demand that risks opening a new Israeli-United States rift, Israeli officials say.

Western diplomats close to the negotiations say banning all enrichment work in Iran is unrealistic given the size of the program, which Tehran equates with national sovereignty.

But Israel has threatened to attack Iran if it deems diplomacy to be ineffective in reining in its arch-enemy, something that could touch off a wider Middle East war.

The six powers and Iran are striving to find an acceptable compromise that would enable Tehran to carry on with limited enrichment that would not give the Iranians the ability to stockpile large amounts of purified uranium, which constitutes the core of atomic bombs if enriched to a high level.

Such restrained enrichment, geared solely to yield energy for civilian uses, would be closely monitored by the International Atomic Energy Agency, the U.N. nuclear watchdog.

Earlier this week Deputy Foreign Minister Sergei Ryabkov said senior officials from the countries involved in the talks now plan to start drafting a text of a possible deal.

"As a result of this round, we should at least get some elements of the agreed text and elements of the common text," he told state-run RIA news agency in an interview. Ryabkov did not give details on what areas the partial agreement he expects to come out of next week's talks in Vienna might cover.

Analysts and diplomats say there is political will on both sides to strike a deal but that it will still be very difficult to overcome key differences, especially on the permissible scope of uranium enrichment.

The six powers want an agreement that would ensure the Islamic Republic could not assemble a bomb any time soon.

After years of an increasingly hostile standoff with the West, Iran's election last year of the pragmatist Hassan Rouhani as president paved the way for a cautious thaw in relations.