Iran will not yield to world powers in the dispute over its nuclear program, President Mahmoud Ahmadinejad said Wednesday in a speech broadcast live on state television.

"The Iranian nation will not retreat one iota in the face of oppressing powers," he said. "The Iranian nation has chosen its path."

The United States and its Western allies accuse Iran of seeking to acquire nuclear weapons and demand that it freeze uranium enrichment. Iran insists that its nuclear program is for peaceful purposes.

Iran says its nuclear program is a peaceful drive to generate electricity so that the Islamic Republic, the world's fourth-largest crude producer, can export more of its oil and gas.

At a meeting with Iran's chief nuclear negotiator in Geneva on Saturday, six world powers gave Iran two weeks to answer calls to rein in its nuclear activities.

Ahmadinejad described U.S. participation in the latest round of nuclear talks a "positive step forward" toward recognizing Iran's right to acquire nuclear technology.

The Iranian president said the United States' decision to attend the talks in Geneva, Switzerland, will help repair America's image in the world.

U.S. Secretary of State Condoleezza Rice accused Iran of not being serious in Saturday's talks despite the presence of a senior U.S. diplomat.

The U.S. participation in the Geneva talks had raised expectations for a compromise formula under which Iran would agree to stop expanding its enrichment activities. In exchange, the six powers — the United States and five world powers — would hold off on adopting new U.N. sanctions against Iran.

The enrichment issue is key to the dispute over Iran's nuclear program because the activity can produce either fuel for nuclear power stations or material used in the fissile core of warheads.

Iran already has defied three sets of U.N. sanctions over its uranium enrichment activity.

But recent Iranian pronouncements suggest the Islamic Republic may be looking to improve ties with the United States, with officials speaking positively of deliberations by the Bush administration to open an interests section in Tehran after closing its embassy here decades ago.

On Wednesday, Ahmadinejad said U.S. Undersecretary of State William Burns, who represented the United States in the Geneva talks, "spoke politely and in a dignified manner."

"You (U.S.) took a positive step. It was a step toward recognizing the rights of the Iranian nation, toward justice, toward repairing your image in the world, toward cleaning 50 years of crimes you committed against the Iranian nation," Ahmadinejad said, addressing thousands of supporters in Yasouj, a town in southern Iran.

Rice has said all six nations were serious about a two-week deadline for Iran to agree to freeze suspect activities and start negotiations or be hit with new penalties.

But Ahmadinejad urged the United States to continue its "positive" attendance in the talks.

"I advise you not to ruin the positive step you took through irrelevant words and claims."

The Associated Press and Reuters contributed to this report.