WASHINGTON - Western powers' strong new sanctions on Iran have failed to push Tehran's leaders toward compromise on their disputed nuclear program, a senior European diplomat said Tuesday.

The official also saw no reason to believe that threats of Western military force would change Tehran's thinking. Talk of the military option "hasn't moved in any way the Iranian regime," he said.

In the grim assessment, the European official - speaking on condition of anonymity because of the sensitivity of the issue - said that while the economic punishments clearly had inflicted pain on Iran, there had been no signal from its leaders that they were willing to yield ground to relieve the international pressure.

Although Iran officially has been calling for new negotiations over its program, the diplomat said he had not seen a single statement to indicate a change in its leaders' views on their nuclear program.

Instead, voices within Iranian President Mahmoud Ahmadinejad's regime insist that there is "no way" it will give ground and that "there is no need for a meeting," he said.

Since the imposition of the latest sanctions last summer, "the whole question has been, 'Is that going to create a new political situation?' " the diplomat told reporters. "We haven't seen anything yet."

Many believe Iran is pursuing a nuclear program to acquire the know-how to build weapons; the Iranian government insists it is interested only in peaceful nuclear projects.

In June, the U.N. Security Council, pressed by the United States and others, imposed sanctions on Iran that targeted individuals and companies with ties to the country's nuclear and military programs.

Later in the summer, the United States, the European Union, Canada, Australia, South Korea, and other industrialized nations added tougher unilateral sanctions, which hit harder at Iran's lucrative energy sector, its trade, and ties to international finance.

By most accounts the Iranian economy, which already had serious problems, has been further damaged by the second set of sanctions.

Yet the impact has been reduced by the willingness of some developing countries - all of which objected to the unilateral sanctions - to keep doing some business with the Islamic Republic's lucrative energy sector. These include China, Russia, Turkey, India, and Brazil.

Iran recently indicated it was willing to restart talks on its nuclear program with world powers after Nov. 10, although key details of the negotiations remain unresolved.

U.S. officials generally have been optimistic on the prospects for negotiating, stressing that sanctions have cut off financial and trade ties and hurt the country's energy business.

On Tuesday, however, Iran's representative to the United Nations' nuclear agency in Vienna, Austria, Ali Asghar Soltanieh, rejected the latest version of a proposal to exchange its nuclear material for isotopes for medical treatments at its hospitals.