British Prime Minister Tony Blair has told parliament the international community needs to send Iran what he calls "a signal of strength" that Tehran must curb its nuclear ambitions.
"It is important surely, at this moment, above all else that we say that they have to come back into compliance with their international obligations and we all support the action necessary to do so," he said. "Now we are pursing that, as I say, in front of the U.N. Security Council but its important that they understand from this House, I hope, that we are united in determining that they should not be able to carry on flouting their international obligations."
The five permanent members of the Security Council - Britain, China, France, Russia and the United States - have joined Germany in agreeing that the Iran issue should be reported to the Council after a meeting this week of the International Atomic Energy Agency in Vienna.
Such a move could lead to sanctions against Iran, and the Iranian leadership has vowed to end all cooperation with the IAEA, if the matter ends up before the Security Council.
British Foreign Secretary Jack Straw has pressed the case with Iranian Foreign Minister Manouchehr Mottaki, who has been in London for a conference on Afghanistan.
A Foreign Office spokesman says the Iranian has been warned not to abandon cooperation with the IAEA, and he has been told Iran must stop making threats.
Meanwhile, in Tehran, Iran's top nuclear negotiator Ali Larijani says the Islamic republic will resume industrial-scale uranium enrichment if its nuclear program is reported to the Security Council.
In a related development, British diplomatic sources confirm that senior Russian and Chinese officials have arrived in Iran for talks on the nuclear issue. A senior British official says the trip is significant because Russia and China are considered sympathetic to Iran.
The official said Iran should take, as he put it, "some pause for thought" from the fact it is getting a united signal from the major powers.