"I know of no such contemplation by the United States," Blair said when asked in Parliament about reports Washington might attack Iran.

In recent days US officials have hardened their tone against the Islamic republic, which US President George W. Bush has already lumped into an "axis of evil".

Blair sent British troops in support of the 2003 US-led invasion of Saddam Hussein's Iraq, which was also part of the "axis of evil."

Last Monday Bush said he could not rule out using force if Tehran failed to rein in its nuclear plans, and US Vice President Dick Cheney said Iran was "right at the top of the list" of global trouble spots.

Cheney also warned that Israel might launch a pre-emptive strike on its own to shut down Iran's nuclear program.

Since the downfall of Saddam Hussein, Israel has come to regard the Islamic Republic as its number one enemy.

While Iran insists its nuclear activities are strictly peaceful, Britain, France and Germany are engaged in diplomatic efforts to secure long-term guarantees that the clerical regime will not seek the bomb.

Blair said "we must do everything we possibly can to send the right signal to Iran" to comply with international regulations on its nuclear program.

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