"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 the U.S.
The United States and other Western nations accuse Iran of seeking to acquire nuclear weapons and demand that it freeze its uranium enrichment program. Iran says its nuclear program is for peaceful purposes. Ahmadinejad on Wednesday again vowed Iran will not "retreat one iota" from pursuing it.
The U.S. participation in the Geneva talks had raised expectations for a compromise under which Iran would agree to stop expanding its enrichment activities. In exchange, six world powers - the U.S., Germany, Britain, France, Russia and China - would hold off on adopting new U.N. sanctions against Iran.
German Chancellor Angela Merkel said negotiators were hearing "very diverse signals" from Iran on its intentions but that she was still counting on a diplomatic solution. "I am counting on that and nothing else," she told reporters Wednesday.
In France, which currently heads the European Union, Foreign Minister Bernard Kouchner said he wasn't surprised that Ahmadinejad "declared he won't budge" because the Iranian president has proved "quasi-unable to show political flexibility."
"It's always disappointing to see how peace efforts are opposed by a tenacity ... that doesn't benefit the Iranian people," Kouchner said.
He said the slow beginning to the Geneva talks did not mean a diplomatic solution would not be found. "The Iranian (negotiators) we are sent are much more flexible than President Ahmadinejad," he told reporters.
The heads of the International Atomic Energy Agency and Iran's top nuclear official plan to meet Thursday, the U.N. agency said without providing details.
The meeting was requested by Gholam Reza Aghazadeh, head of Iran's Atomic Energy Organization, said a diplomat close to the U.N. nuclear watchdog. The diplomat spoke on condition of anonymity because the information was confidential.
U.S. Secretary of State Condoleezza Rice on Monday accused Iran of not being serious at the Geneva talks. She said Iran had given the run-around to the envoys, while all six nations were serious about a two-week deadline for Iran to agree to freeze suspect activities and start negotiations or else be hit with new penalties.
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 to the possibility of opening an interests section in Tehran after closing its embassy there decades ago.
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," he said.
