By Parisa Hafezi and Zahra Hosseinian
The comments by the conservative president, who is seeking a second term in a June 12 election, are likely to further disappoint the U.S. administration of President Barack Obama, which is seeking to engage Iran diplomatically.
The United States, Russia, China, France, Germany and Britain said in April they would invite Iran to a meeting to try and find a diplomatic solution to the nuclear row.
The West accuses Iran of secretly developing atomic weapons. Iran, the world's fifth-largest oil exporter, denies the charge and says it only wants nuclear power to generate electricity.
Breaking with past U.S. policy of shunning direct talks with Iran, Obama's administration last month said it would join nuclear discussions with Tehran from now on.
Ahmadinejad proposed a debate with Obama at the United Nations in New York "regarding the roots of world problems" but he made clear Tehran would not bow to pressure on the nuclear issue.
"Our talks (with major powers) will only be in the framework of cooperation for managing global issues and nothing else. We have clearly announced this," Ahmadinejad said.
"The nuclear issue is a finished issue for us," he told a news conference. "From now on we will continue our path in the framework of the (U.N. nuclear watchdog) agency."
He was asked about a so-called "freeze-for-freeze" proposal first put forward last year under which Iran would freeze expansion of its nuclear program in return for the U.N. Security Council halting further sanctions against Tehran.
NO COOPERATION WITH NORTH KOREA
Western diplomats say the proposal remains on the table and one such source said it was made clear in a meeting with Iran's chief nuclear negotiator Saeed Jalili in Tehran on Sunday.
Ahmadinejad in April announced Iran had prepared its own proposals to end the stalemate and he said on Monday they would refer to Iran's opposition to weapons of mass destruction.
Obama has offered a new beginning of diplomatic engagement with Iran if it "unclenches its fist," but Washington has not ruled out military action if diplomacy fails.
Last week, the U.S. president set a rough timetable for his diplomatic outreach to Tehran for the first time, saying he wanted to see serious progress by the end of the year.
Iran says it is ready for "constructive" talks but has repeatedly rejected demands to halt sensitive uranium enrichment which can have both civilian and military purposes.
Ahmadinejad, facing a challenge in the election from moderates advocating detente with the West, has made angry rhetoric against the United States and it allies his trademark since he came to power in 2005.
He said Iran had no missile or nuclear cooperation with North Korea, after Pyongyang conducted a second and far more powerful nuclear test. Former U.S. President George W. Bush branded both countries as part of an "axis of evil."
"In principle we oppose the production, expansion and the use of weapons of mass destruction," Ahmadinejad said.
Military experts say Iran's Shahab-3 missile is based on the North Korean Nodong missile. Tehran says Shahab-3 has a range of 2,000 km (1,200 miles), which defense analysts say would put Israel and U.S. bases in the Gulf within reach.
Iran last week said it test-fired another missile — Sejil 2 — with a similar range.
(Writing by Fredrik Dahl)
