Iran has said it plans to build an experimental nuclear fusion reactor, ignoring calls from the West that Tehran suspend sensitive nuclear work.

In 2006, Iran said it was pressing ahead with research tests on nuclear fusion, a type of atomic reaction which has yet to be developed for commercial power generation.

The US and the EU suspect that Iran is trying to build an atomic bomb, and have imposed sanctions on it in a drive to convince it to drop sensitive nuclear work.

Tehran says its nuclear programme is for civilian purposes only.

Iran also warned it would stop trading with countries that impose restrictions on its assets abroad.

The US, the UN and the EU have imposed new restrictions on Iran over its nuclear enrichment activities.

The fourth round of UN sanctions calls for measures against new Iranian banks abroad if a link to the nuclear or missile programmes is suspected and for vigilance on transactions with any Iranian bank, including the central bank.

‘Any country that creates limitations for Iran's assets, we will stop trading with them,’ Hamid Borhani, deputy head of the Central Bank of Iran, told the semi-official Mehr news agency. ‘We have to protect our assets.’

Iran is the world's fifth-largest crude oil exporter.