Zarif said that Iran and the United States have reached “very fine details,” but stressed that “more work” is needed during the nuclear talks under way this week in the Swiss city of Lausanne.

Iranian Foreign Minister Mohamamd Javad Zarif said that Iran and the United States have reached “very fine details,” but stressed that “more work” is needed during the nuclear talks under way this week in the Swiss city of Lausanne.

Meanwhile, heplayed down the chances of reaching a nuclear agreement, saying that other world powers negotiating with Iran are unlikely to be required in Lausanne to approve a deal.

"I don't think their presence will be needed in this round because when the solutions are found and we approach a deal, then all the foreign ministers of the negotiating parties should come," said Zarif, who has been holding two-way talks with US Secretary of State John Kerry.

"They might come, but at this stage I wouldn't think they are needed," he repeated, referring to the top diplomats of the so-called P5+1 (Britain, China, France, Russia, the United States, and Germany).

On day three of talks with Kerry, Zarif said "there are differences and we are trying to reduce them," by Thursday evening, with political directors of the 5+1 countries starting to arrive in Lausanne on Wednesday.

"We must find solutions," state media quoted him as saying.
"The question of an agreement comes when we have solutions written on paper, and to write the solutions we need the experts more than foreign ministers."

The minister said that the two sides had reached "very fine details in the negotiations and details always require more work".

Iran and six world powers aim to agree the framework of a nuclear deal by March 31 and then have a full deal by July 1.