Iran returned to nuclear talks with world powers after furious diplomacy to salvage the negotiations on a uranium enrichment deal which had come to a standstill.

Iranian, US, Russian and French officials resumed their talks at the headquarters of the International Atomic Energy Agency in Vienna late on Tuesday after the American and Iranian sides met separately under the auspices of the IAEA.

The talks, which started on Monday, had appeared on the verge of collapse earlier on Tuesday when the Iranian delegation left the building without any explanation and after Tehran said it did not want Paris to be part of a deal.

But all sides eventually returned to the negotiating table for about an hour and IAEA chief ElBaradei, who attended the talks, said they would meet again on Wednesday.

The talks are over a proposal for Russia and France to enrich below-weapons grade uranium for Iran.

Western powers want greater control of Iran’s uranium which they fear is being used to build a nuclear bomb.

“We still hope to be able to reach an agreement. It’s a complex process,” ElBaradei told reporters.

“There are technical aspects, many technical issues that we have to hammer out. It is of course a question of confidence building, of guarantees,” he said.