But last week US President Donald Trump announced he was leaving the deal and reimposing sanctions.

After long negotiations, Iran agreed in July 2015 to freeze its nuclear programme in return for the repeal of punishing international sanctions.

Mohammad Javad Zarif will meet with his counterparts from Britain, France and Germany -- the three European nations involved in the landmark deal who are incensed by Washington's abandonment of the pact.

rallying diplomatic support for the country's nuclear deal after the Trump administration's abrupt withdrawal.

Iran's foreign minister is due to land in Brussels later Tuesday on the final leg of a global tour

Zarif's has since embarked on a whirlwind global tour, visiting both Russia and China, the two other signatory nations, in a bid to bolster support.

Washington's decision to go against its European allies' advice and abandon the deal has pushed them closer to Beijing and Moscow as diplomats scramble to keep the pact alive.

"The agreement with Iran is working, we must do our utmost to preserve it," Maja Kocijancic, spokeswoman for the head of European diplomacy Federica Mogherini, told AFP ahead of Zarif's arrival.

Iran has said it is preparing to resume "industrial-scale" uranium enrichment "without any restrictions" unless Europe can provide solid guarantees that it can maintain trade ties despite renewed US sanctions.

On Monday Zarif met with his Russian counterpart Sergei Lavrov, a day after visiting leaders in Beijing.

"The final aim of these negotiations is to seek assurances that the interests of the Iranian nation will be defended," Zarif said at the start of a meeting.

After the talks, Zarif praised the "excellent cooperation" between Moscow and Tehran and said Lavrov had promised him to "defend and keep the agreement".

Lavrov, for his part, said Russia and Europe had a duty to "jointly defend their legal interests" in terms of the deal.

'Malign behaviour'

On Monday Zarif also sent a letter to the United Nations in which he accused the US of showing a "complete disregard fo

r international law" in pulling out of the deal.

Russian President Vladimir Putin has already spoken with German Chancellor Angela Merkel and Turkey's President Recep Tayyip Erdogan about efforts to save the accord, after voicing his "deep concern" over Trump's decision.

And on Monday Putin met Yukiya Amano, the head of the International Atomic Energy Agency, telling him that Russia was "ready to continue to uphold the Iran nuclear deal despite the withdrawal of the United States".

Analyst say Trump's move to ditch the nuclear deal has brought Europe, Moscow and Beijing together.

"(European) cooperation with Russia, which until recently seemed impossible because of the Skripal (spy poisoning) case, with the expulsion of diplomats and the reduction of contact, is now receiving a fresh boost," said Andrei Baklitsky of the Moscow-based PIR Center nuclear safety NGO.

"The Europeans, after the withdrawal of the US from the deal, have found themselves forced to save the Joint Comprehensive Plan of Action themselves," he told AFP, referring to the official name of the nuclear deal.

Moscow would have to play a key role in ensuring Tehran does not resume its nuclear programme, he added.

On Sunday, US Secretary of State Mike Pompeo said Washington still wants to work with Europe to counter Iran's "malign behaviour" and was working hard to thrash out a more wide-ranging deal with its European partners.

But while he talked up the prospect of renewed coordination with America's allies, another top aide reminded Europe its companies could face sanctions if they continue to do business with the Middle Eastern power.

Russian efforts to save the accord will boost its role as a power player in the Middle East, after its intervention on the side of Bashar al-Assad's regime in Syria.

This, along with its diplomatic moves to orchestrate an end to the Syrian conflict, has put Moscow at loggerheads with the US and Europe, which have intervened against the regime.

Merke

l is set to visit Russia and meet Putin in the Black Sea resort of Sochi on Friday, while French President Emmanuel Macron will be in Saint Petersburg later this month for an economic forum.

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