Tehran: Iran and its powerful ally Russia on Tuesday slammed new Western sanctions imposed on Tehran over its suspect nuclear programme, saying they were illegal and futile.

The unilateral measures against Iran's financial, petrochemical and energy sectors announced on Monday by the United States, Britain and Canada amounted merely to "propaganda and psychological warfare," Iranian foreign ministry spokesman Ramin Mehmanparast said.

They were "reprehensible" and would prove ineffective, he said.

Russia -- which with China had blocked any possibility of the Western steps going before the UN Security Council for approval -- took a sterner view, saying in a foreign ministry statement the sanctions were "unacceptable and against international law."

The declarations set the stage for a hardening of diplomacy over Iran and its nuclear programme. The issue has already generated speculation that Israel is mulling air strikes against Iranian nuclear sites.

The United States and its allies cited a November 8 report by the UN's International Atomic Energy Agency asserting "credible" evidence of Iranian research programmes for nuclear weapons as justification for their new sanctions.

Iran, which has dismissed the IAEA report as "baseless" and biased, insists its nuclear programme is for exclusively peaceful, civilian purposes.

Iran's Foreign Ministry Spokesman Mehmanparast said the sanctions "show the hostility of these countries towards our people."

"With these resolutions.... they think they can pressure our people to give up their rights (to nuclear energy). But they're wrong," Mehmanparast said.