Six world powers met on Thursday in New York behind closed doors to discuss possible steps over the Iranian nuclear issue.

The permanent representatives of the five permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- and Germany, met for more than three hours at Britain's UN mission.

"I don't think any of us want to impose sanctions," Russia's ambassador to the UN Vitaly Churkin told reporters after the meeting.

"But what we want to have is a diplomatic solution and all sorts of constructive proposals have been made to Iran," he said. "If Iran wants to negotiate, they should start negotiating."

China's UN Ambassador Li Baodong told reporters that Thursday's negotiations were "constructive" and that the "dual track approach is actually focused on diplomacy."

U.S. ambassador to the UN Susan Rice said the meeting was "worthwhile," but she did not go into the details.

The United States and other western countries have been pushing for a fourth round of UN sanctions to restrict Iran's nuclear efforts, which they say are aimed at developing nuclear weapons.

Iran has denied the western accusation and stressed its nuclear program is solely for peaceful purposes and intended to generate electricity for its population.

Since 2006, the Security Council has slapped three rounds of sanctions against Iran.