Chief nuclear negotiator Hassan Rowhani put forward the offer, which was "widely welcomed", during talks in Paris and Berlin, a fellow member of his team, Hossein Moussavian, told state television.

"The idea is to seek technical assistance from the IAEA (the UN atomic watchdog), which is responsible for guaranteeing that countries do not deviate towards building an atomic bomb," Moussavian said.

Britain, France and Germany have been trying to persuade Tehran permanently to abandon uranium enrichment, which can be a key step to developing nuclear weapons, in return for a package of trade deals.

"If the three countries agree, I have high hopes that our work will get somewhere more quickly," added Moussavian.

Rohani had given French and German officials "very concrete guarantees that Iran will not seek in any way to produce nuclear armaments," he added.

"On this point, Iran is ready to be fully flexible on all points of cooperation to create trust," said Moussavian.

Israel and the United States have repeatedly charged that Iran is covertly trying to develop a nuclear arsenal. Tehran denies the accusations.