Iranian President Mahmoud Ahmadinejad said there isn't a "damn thing" Israel can do to stop its nuclear program, Reuters reported.

"The Zionist regime (Israel) and its (western) backers cannot do a damn thing to stop Iran's nuclear work," Ahmadinejad said in a televised speech, according to Reuters.

Iran said Wednesday it will enrich uranium to a higher level on its own, the latest indication the country was rejecting a U.N.-backed proposal aimed at thwarting any effort by Tehran to make material for a nuclear weapon.

President Mahmoud Ahmadinejad made the comment after expressing frustration with the ongoing negotiations over the proposal that Iran exchange the bulk of its low-enriched uranium for more highly enriched fuel rods to be used in a medical research nuclear reactor.

Low-enriched uranium can be used as fuel for nuclear energy, but enriched to much higher levels, it can be used as material for a weapon. Iran currently has one operating enrichment facility that has churned out around 3,300 pounds of 3.5 percent enriched uranium over the past years, but the country needs fuel enriched to 20 percent to power a medical research reactor.

"I declare here that with the grace of God, the Iranian nation will produce 20 percent (enriched uranium) fuel and anything it needs itself," Ahmadinejad told a cheering crowd of thousands in the central city Isfahan. "We told them, give us the 20 percent fuel (in an exchange)," he said. "But then they started adding conditions. So we said, if you want to give us the fuel we'll take it. If not, then fine and goodbye."

Ahmadinejad, in a speech Tuesday night, indicated Iran was through negotiating the nuclear issue.

"We were interested, from the beginning, in solving all the problems related to the nuclear issue," he said. "Now, the issue, in our opinion, is over."

And on Sunday, Ahmadinejad announced Iran would build 10 more uranium enrichment facilities, despite the widespread belief that the country simply does not have the resources to match its boasts.

Though Iran has yet to lodge an official rejection of the U.N. nuclear watchdog's proposal on shipping out uranium, the series of defiant statements over the past few days have sent a clear signal that the idea is all but dead.

British Prime Minister Gordon Brown said last month that the U.N. offer has been "comprehensively rejected" by Iran.

The U.N. nuclear watchdog, the International Atomic Energy Agency, passed a resolution on Friday demanding Iran to cease all enrichment immediately and halt construction on a recently revealed uranium enriching facility hidden in a mountain.

Iran reacted angrily by promising to build 10 new plants and on Tuesday Ahmadinejad said he was considering decreasing cooperation with the IAEA, the world's only eye into the secretive country's nuclear program.

In his speech Wednesday in Isfahan, Ahmadinejad further slammed the IAEA as being a tool of the Western powers hostile to Iran.

"They (Western countries) once again showed that they are not committed to the law. They make use of international bodies as tools ... the era of such childish games are over," he said.

While Iran maintains its nuclear program is only for peaceful purposes to produce electricity, the process of enriching uranium for fuel can be taken further, to levels around 90 percent, and produce material for a nuclear warhead.

The idea behind the swap was to get the bulk of Iran's uranium out of the country so it would not have enough material build a bomb.

The Associated Press contributed to this report.