Just days ahead of a new report by the U.N. nuclear watchdog, hardline President Mahmoud Ahmadinejad said Wednesday that Iran has brought world powers "to their knees" and successfully resisted U.S.-led efforts to get Tehran to halt its uranium enrichment.

Ahmadinejad delivered a defiant speech to cheering supporters Wednesday in southern Iran, ahead of a new report by the International Atomic Energy Agency on the country's disputed nuclear program that Washington and some of its allies fear is aimed at building nuclear weapons.

"They (U.S. and its allies) expected the Iranian nation... to surrender after a resolution is issued or sanctions are imposed, but today... it has brought all big powers to their knees," Ahmadinejad told supporters in Bandar Abbas, in comments broadcast live on state television.

The fiery leader said Iran would not stop enriching uranium -- a process that yields material that can be used to produce nuclear fuel or bombs -- under any conditions. Tehran says its program is to generate fuel only.

"The Iranian nation considers nuclear energy its definite right and does not accept any additional and cruel rules," Ahmadinejad said, alluding to a possible new round of United Nations sanctions.

His speech drew chants of "Nuclear energy is our definite right!" from the crowd.

Iran says it has a right under the Nuclear Nonproliferation Treaty to enrich uranium for peaceful means. But it has been slapped with two rounds of U.N. sanctions over its refusal to stop enrichment.

The measures ordered all countries to ban the supply of specified materials and technology that could contribute to Iran's nuclear and missile programs, and also imposed an asset freeze on key Iranian companies and individuals named by the United Nations. Iran condemned the resolutions as "invalid" and "illegal."

Addressing the U.S. directly, Ahmadinejad warned Wednesday that America and its allies would face a determined nation "if you start a new game." He did not elaborate, but was likely referring to Washington's efforts to push for a new round of U.N. sanctions.

Such efforts come in the wake of a U.S. intelligence report in December that concluded Iran had stopped its nuclear weapons program in late 2003 and has not resumed it since. Iran says it never had a weapons program.

In November, an IAEA report said Iran had been truthful about its past uranium enrichment activities.