Russia had proposed the meeting for the European Union and Iran to "talk about getting back to talks," a diplomat said, referring to negotiations on winning guarantees Tehran will not make nuclear weapons.

The talks collapsed last August when Iran resumed nuclear fuel work that it had earlier suspended in order to make the negotiations possible.

Iran on Wednesday began to convert a new batch of uranium ore into the gas that is the feedstock for enriching uranium into what can be reactor fuel or atom bomb material, defying international requests not to do so.

The UN watchdog International Atomic Energy Agency (IAEA) had urged Iran in September not to resume uranium conversion, and is to meet on the matter next Thursday in Vienna.

"Moscow is off, so we go to the board without that kind of prelude," a European diplomat said, referring to the IAEA's board of governors' meeting.