Vienna - The five nuclear weapons states and Germany on Tuesday offered Iran direct dialogue to solve the nuclear spat, while also calling on leaders in Tehran to obey the demands of the United Nations Security Council.

Britain, China, France, Russia and the United States - the permanent members on the Security Council - issued their statement together with Germany to the 35-country board of the International Atomic Energy Agency (IAEA) in Vienna.

France's IAEA governor Olivier Caron said in the statement that "we remain firmly committed to a comprehensive diplomatic solution, including through direct dialogue" - an indirect reference to plans by the new US administration to sit down in bilateral talks with Iran.

The statement came one day after US ambassador Gregory Schulte outlined his country's intention to "strengthen diplomatic efforts" to solve the nuclear stand-off.

So far, Tehran has ignored three round of UN sanctions aimed at getting Iran to stop its uranium-enrichment programme, and has not taken up the six countries' offer of economic and political cooperation in return for such a halt.

The six countries on Tuesday also noted that IAEA chief Mohamed ElBaradei had expressed "serious concern" regarding Iran's refusal to answer questions on past research that could have been related to nuclear weapons.

European Union members appeared to put more pressure on Iran in their joint statement than the nuclear weapons states and Germany.

The EU said it was "deeply disappointed" and spelled out the questions Iran should answer, including Tehran's reason for acquiring a sensitive document apparently related to making a nuclear warhead.

Iran has stated that its uranium enrichment facility in Natanz produces fuel for a civilian nuclear reactor, and not for atomic bombs. The country has dismissed indications that it had conducted weapons-related research in the past. (dpa)