World powers meeting in Vienna have warned Iran to stick to terms of a nuclear accord during talks that Tehran have called the 'last chance' to save the crumbling pact a year after the United States abandoned it.

Envoys from Britain, Germany, China, Russia, and France, held a quarterly meeting with Iran in Vienna on June 28 to discuss sticking to the terms of a 2015 deal that limits the enrichment and stockpiles of uranium and reduces nuclear capabilities in return for relief from international sanctions.

The warning comes in the face of comments from Brian Hook, U.S. special representative on Iran, who said earlier in the day from London that Washington will maintain its hard-line stance toward Tehran and will "intensify" sanctions until the country becomes a "normal state."

Tensions have risen sharply since May 2018, when the U.S. unilaterally abandoned the Joint Comprehensive Plan of Action (JCPOA) while imposing more than 1,000 sanctions on Iran and parties that might trade with it.

One of the main targets of the sanctions is cutting off Iran's lifeline, its oil sales, and forcing Iranian officials to the negotiating table.

Hook said Washington's moves are set to cost Iran some $50 billion in oil revenues, and that European companies have a choice of either "doing business with the United States or do business with Iran."

Reliant on oil sales for much of its foreign revenue, Iran's crude oil output has dwindled to less than 500,000 barrels a day. That compares with May's production levels of some 2.8 million barrels per day.

'We will sanction any imports of Iranian crude oil.... There are right now no oil waivers in place,' Hook said.

In recent weeks Iran has said it is no longer bound to implement all of the terms of the JCPOA, which is verified by the Vienna-based International Atomic Energy Agency (IAEA), given the U.S.'s departure from the accord.

It has said it is on the brink of exceeding the 300 kilogram limit of enriched uranium allowed under the pact, and that the Vienna talks may be 'the last chance for the remaining parties" to save the deal.

The prospect that Tehran could violate its nuclear commitments only a week after U.S. President Donald Trump called off air strikes against Iran at the last minute has added to the sense of urgency to find a way out of the crisis at the Vienna meeting.

Trump, however, said on the sidelines of the Group of 20 summit in Japan on June 28 that "there's no rush" right now with regard to Iran.

'They can take their time. There's absolutely no time pressure. I think in the end, hopefully, it's going to work out. If it does, great -- and if it doesn't, you'll be hearing about it,' he said as he greeted Indian Prime Minister Narendra Modi on the sidelines of a G20 summit in Osaka.

With reporting by AP, Reuters, and Financial Times

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