BRUSSELS - European Union governments pledged on Monday to suspend some sanctions against Iran as soon as the UN nuclear watchdog verifies that Tehran has curbed its atomic work under last month's landmark agreement.

No date has been set for the deal between six world powers and Iran to take effect, and talks on implementing it ran into trouble last week after the United States expanded its sanctions against the Islamic Republic.

Under the accord, Iran is supposed to suspend its most sensitive nuclear work while governments in the United States and Europe ease some economic restrictions, in a first step towards a comprehensive settlement of the decade-old dispute.

The sequence of lifting sanctions and Iran's nuclear steps has been an issue in discussions between Iran and the six powers - the United States, Russia, China, France, Britain and Germany - on implementing the breakthrough interim agreement.

The International Atomic Energy Agency (IAEA), a UN body, is expected to verify that Iran has taken the agreed steps.

In a statement, EU foreign ministers said Iran had to implement its side of the deal in good faith.

"For its part, the Council is committed to ... suspend those EU sanctions as set out in the (agreement) immediately after the IAEA has verified the implementation of the nuclear-related measures by Iran," they said.

Western nations imposed sanctions on Iran over suspicions that it is covertly seeking a nuclear weapons capability. Tehran says its nuclear program is only for civilian purposes.

Iran's Deputy Foreign Minister Abbas Araqchi travelled to Brussels on Monday to meet EU foreign policy chief Catherine Ashton, who oversees contacts with Iran for the six nations, and other officials to discuss implementation of the nuclear deal.

Ashton said before the EU foreign ministers' meeting that she expected experts from Iran and the six nations to meet very soon to resume talks on how it would be put into practice.

Britain's Foreign Secretary William Hague cautioned, however, that these discussions could take time.

"While we have reached the interim deal, the details of implementation remain to be negotiated and there will be many difficulties in that, so we shouldn't be surprised if these talks are difficult," he told reporters.

Hague also said Western governments would keep up economic pressure on Iran, something they believe helped bring it to the negotiating table and paved the way for the November agreement.

"We have to maintain our vigilance on sanctions and maintain the sanctions that we are not suspending so that Iran has a clear incentive to make a comprehensive deal," he said.

Scope for diplomacy widened after Iran elected the pragmatic Hassan Rouhani as president in June, and he promised to reduce Tehran's isolation and get sanctions eased. But after years of mutual distrust any progress will likely be fragile.

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