US spying on nuke sites from space: Iran

"We believe the United States has been spying against Iran for some time using satellites and other tools," he was quoted as saying on the official IRNA news agency, when asked about U.S. denials that it was using drones over Iran.

Yunesi denied allegations by Washington that Tehran was secretly trying to develop nuclear weapons. Iran says its nuclear activities are for generating electricity.

"Our nuclear and military activities are transparent. We have nothing to hide," he said.

The Washington Post, citing information from unnamed US officials, reported this week that the United States had been flying drones into Iran for the past year looking for evidence of nuclear weapons programmes.

The pilotless planes flew into Iran from US military bases in Iraq and used radar, photography and air filters to detect signs of nuclear activity, the newspaper said.

The Iranian air force was ordered in December to shoot down any unknown or suspicious flying objects over its territory.

Yunesi said that the air force was ready to confront any threat.

"If any of these bright objects come close, they will definitely face our fire," the minister said.

US officials have stressed diplomacy but have not ruled out an attack on nuclear sites which Iran insists are only to generate electricity.

Iran has repeatedly warned the United States not to attack its nuclear facilities, saying talks with the European nations might produce a deal to defuse the dispute.

France, Britain and Germany have tried in talks with Iran to persuade the oil-rich country to drop its nuclear fuel-making program in return for economic incentives.

Yunesi reiterated previous statements by top officials that Iran would not tolerate any acts of aggression, particularly from its arch-foe the United States.