Iran proposed changes to a U.N.-drafted nuclear fuel deal on Thursday, Iranian media said, making demands that appeared to challenge the basis of the agreement with the United States, France and Russia.

The U.N. International Atomic Energy Agency (IAEA), which had requested a reply by last Friday, said its chief, Mohamed ElBaradei, had now received an "initial response" from Tehran.

"(ElBaradei) is engaged in consultations with the government of Iran as well as all relevant parties, with the hope that agreement on his proposal can be reached soon," the IAEA said in a statement. It gave no further details.