"Splits between the parties are very visible, that is to say between the United States and the Europeans on one side and Russia and China on the other," foreign ministry spokesman Mohammad Ali Hosseini told reporters.
"These two countries have completely different positions to the Europeans. Russia does not want sanctions and does not want to close the path of negotiations, and the Chinese have a similar position," he added.
The United Nations Security Council's five veto-wielding members -- Britain, China, France, Russia and the US -- as well as Germany have been discussing a draft resolution on sanctions put forward by European countries.
But in a sign of the difficulty in reaching an agreement, Russian Foreign Minister Sergei Lavrov rejected the proposed sanctions, arguing that they did not advance objectives agreed on by the six world powers.
The Chinese stance has yet to become clear, although Beijing -- like Moscow -- is an economic ally of Iran and traditionally reluctant to use sanctions as diplomatic leverage.
Hosseini meanwhile played down Iran's decision to start enriching uranium from a second cascade of 164 centrifuges at its nuclear plant at Natanz in the centre of the country, a move greeted with suspicion by the West.
"The second cascade is part of the research activities of the country which are in line with the nuclear Non-Proliferation Treaty," he said.
"There is nothing new. It is the continuation of legal activities under the control of the International Atomic Energy Agency (IAEA), and there is no deviation," Hosseini added.
Iran vehemently rejects US allegations that its nuclear programme is aimed at making nuclear weapons, saying the drive is solely aimed at providing energy for civilians.

Copyright AFP (Agence France-Presse), 2006