Germany Sunday called for restraint from Iran amid an escalation in tensions over Tehran's disputed nuclear programme and a threat to immediately cut off oil exports to Europe.

Foreign Minister Guido Westerwelle told the Welt am Sonntag newspaper that the crisis-wracked European Union would not allow Iran to push it into a corner with a potential cut in oil supplies.

"In Iran we are seeing a regrettable and dangerous escalation in rhetoric," he said. Iran's leaders "must finally understand that they have the key to reducing tensions in their hands".

Westerwelle said the EU would not allow "threats" to lead it away from "the path of decisiveness against Iran acquiring an atomic weapon".

"We will find ways in the EU to compensate for delivery stoppages," he said.

Tehran has reacted fiercely to new sanctions targeting its oil and finance sectors, notably the EU's announcement Monday that it would ban all Iranian oil imports within the next five months, after weak economies such as Greece and Spain had found alternative suppliers.

Iran's parliament is considering a draft law that would pre-empt the EU ban by cutting off shipments to Europe immediately. The bill could be debated Sunday.

The EU imported some 600,000 barrels per day of Iranian oil in the first 10 months of last year -- equivalent to nearly 20 percent of Iran's exports -- making it the key market alongside India and China.

Iran has signalled willingness to resume talks on its nuclear activities with world powers Britain, China, France, Russia, the United States, and Germany that collapsed a year ago.

But thus far it has not replied to a letter sent three months ago by EU foreign policy chief Catherine Ashton offering a return to the negotiations.