Hossein Moussavian, an aide to the head of Iran's nuclear programme, Hassan Rohani, told state television that Tehran's pursuit of enrichment has been the main concern of its European partners.

"The Europeans know that if Iran masters the technology for enrichment it has a potential (military) nuclear capability and that will change the (political) equation" in the region, he said.

But Moussavian said that Iran was prepared to guarantee that enrichment would not be used for military purposes.

"We are prepared to build trust and provide a guarantee that our enrichment activities will always be peaceful."