Bells chimed across Iran yesterday to mark the return from exile in 1979 of Ayatollah Ruhollah Khomeini, the trigger for a revolution which spawned an Islamic state now engulfed in a deep political crisis.

To mark Khomeini's triumphant return after 15 years in exile, all schools, trains and boats rang their bells at precisely 9:33 am (0603 GMT), the moment his plane touched down at Tehran’s Mehrabad airport on February 1,1979.

President Mahmoud Ahmadinejad and other senior Iranian officials paid homage to the cleric at his mausoleum in southern Tehran.

Monday marked the start of 10 days of celebrations which culminate on February 11, the 31st anniversary of the fall ofthe US-backed shah who had ruled the country for nearly four decades but who fled two weeks before Khomeini's return.

On his arrival on board an Air France jet 31 years ago, the bearded Khomeini, then 76, had vowed to establish a new government in Iran.

"I will appoint a government. I will slap this government on the mouth," he said in an address at Tehran’s Behesht Zahra cemetery, referring to the government of the shah's last prime minister Shahpour Bakhtiar.

The charismatic cleric assumed the role of Iran's supreme leader, which he held until his death in 1989.

During his conservative rule, Iran became embroiled in a brutal conflict with Saddam Hussein's neighbouring Iraq. Over a million people were killed on both sides during the war.

Khomeini had also backed Islamist students who stormed the US embassy in Tehran in November 1979 and took its personnel hostage for 444 days, prompting Washington to severe ties with the Islamic republic.