Some Iranian lawmakers are saying Iran will reject a U.N.-backed proposal for Iran's uranium to be enriched abroad.
The semi-official ISNA news agency quotes a prominent conservative lawmaker laeddin Boroujerdi saying Iran will not send away any of its 1,200 kilograms of enriched uranium.
France, Russia and the U.S. are urging Iran to trade about 7 percent of its low-enriched uranium for nuclear fuel, which would assuage international fears the stockpile would be used to make a bomb.
Another conservative lawmaker, Hossein Naqvi Hosseini, said Iran could not trust the international promises, therefore it could not accept such an agreement.
He said Iran could buy uranium directly from another country or enrich it themselves.
Russia's president Dmitri Medvedev says if Iran "takes a less constructive stance" in international talks, the possibility of further sanctions could not be excluded.
In an interview with Germany's Der Spiegel magazine, Mr. Medvedev said sanctions usually represent a step in a "dangerous direction." But he said they may be necessary, nonetheless.
The International Atomic Energy Agency says it has not yet heard a formal response to the proposal from Iran.
The U.N. Security Council has hit Iran with three sets of sanctions for its refusal to stop enriching uranium, a process that can be used to make nuclear weapons.
Iran says its atomic program is aimed at generating electricity.
Israel's deputy foreign minister says Israel will attack Iran if it continues on a path of nuclear defiance. Danny Ayalon told Britain's Sky News that Iran has expressed no desire to halt its nuclear program.
He accused Iran of conducting stalling tactics in hopes of "buying time" on its uranium enrichment work.
Israel perceives Iran as its greatest threat in part due to remarks by Iran's president calling for Israel to be "wiped off the map."