Russia has spoken out more strongly than ever against Iran, warning that it may consider tougher sanctions against the country should it fail to accept a Western-backed nuclear proposal.

In an interview with the German weekly Der Spiegel on Saturday, Russian President Dmitry Medvedev said that, much to his reluctance, he would be forced to sign off on US-led sanctions on Iran.

"I do not want that all this ends up with the adopting of international sanctions because sanctions, as a rule, lead in a complex and dangerous direction," AFP quoted Medvedev as saying.

"[But] if the Iranian leadership takes a less constructive position, then in theory anything is possible," he added.

"If there is no movement forward then no one is going to exclude such a scenario."

Medvedev added that he thoroughly discussed the issue with US President Barack Obama on the sidelines of the UN General Assembly meeting in New York in September.

The comments were released by the Kremlin only hours after a leading Iranian lawmaker, Alaeddin Boroujerdi, ruled out an IAEA-brokered proposal to export low-enriched uranium (LEU) abroad for further refinement.

"(Iran) is not going to give the other side any of the produced 1,200 kilograms of its fuel to receive 20-percent fuel. (The shipment) will not be sent, either in stages or altogether [a single batch], and it is ruled out," said Boroujerdi, who chairs the Parliament (Majlis) National Security and Foreign Policy Committee.

Tabled by the International Atomic Energy Agency (IAEA), the proposal requires Iran to ship as much as 70 percent of its LEU out of the country for processing into fuel for the Tehran research reactor.

Iranian officials have welcomed foreign cooperation on fuel supply, but have rejected the idea of sending out the bulk of its uranium stock in one batch, saying there are no guarantees that Western countries would keep their end of the bargain.

In the early 1970s, Iran made a deal with France under which it was expected to receive around 50 tons of UF-6 gas, which can be turned into enriched uranium.

France, however, later reneged on the deal and to this day has refused to deliver the uranium-hexafluoride to Iran.

Moreover, Iran, has a 10-percent stake in France's Eurodif nuclear facility and is entitled to the plant's output, but has never received any nuclear material.

"Iran is a sleeping partner in Eurodif [and has] never received a single gram of enriched uranium from France," said a spokesman for the state-controlled nuclear reactor builder Areva that owns the remainder of the Eurodif plant.