An Iranian official says his country will refuse requests to freeze its uranium enrichment program in exchange for a pledge of no new U.N. Security Council sanctions.

Keyvan Imani's comments cast doubt on the success of talks between senior envoys from Iran and the six countries trying to persuade it to compromise on its nuclear program.

The six nations hope Iran will agree to stop expanding its uranium enrichment program. In exchange, they offer to hold off pushing for new U.N. Security Council sanctions against the Islamic Republic.

But Imani, speaking to reporters shortly after the talks began Saturday, said there was no chance Iran would suspend.