Members of the European Union have warned Iran of fresh sanctions over its controversial nuclear programme.

British Foreign Secretary William Hague said sanctions are already impacting Iran, but that it was "necessary to increase the pressure on Iran, to intensify sanctions, to add further to the EU sanctions," he said to reporters after informal talks with other EU foreign ministers.

German Foreign Minister Guido Westerwelle expressed frustration over the lack of progress and said Iran has made no “substantial offer" to make clear the intentions of its nuclear programme.

Russian Minister Sergei Lavrov criticised the sanctions on Iran, saying it harmed their economic interests as they were "increasingly becoming extra-territorial in nature."

But other EU ministers criticised Russia’s position.

"If Mr Lavrov wants to avoid sanctions it would be simpler to take part in a political consensus at the Security Council," said Belgium's Foreign Minister Didier Reynders.

"If he criticizes the sanctions because they affect the economy, we should also, we Italians, and we Europeans, be the first to criticise the sanctions," said Giulio Terzi, Italy's foreign minister.

"The question is not economic interest, the question is the security of our citizens, not only in the neighbouring countries, but the security of all Europe in the face of a potential threat from a nuclear armed Iran."