Celebrations to mark 40th anniversary of Islamic Revolution begin in Iran

Iran is celebrating the 40th anniversary of its Islamic Revolution that toppled the U.S.-backed Shah, overturned 2,500 years of monarchical rule and brought hard-line Shia clerics to power.

The anniversary starts every year on 1 February – the day Ayatollah Ruhollah Khomeini returned from France in 1979, after 14 years in exile, to become the supreme leader of the Islamic Republic of Iran.

Across the country on Friday, sirens rang out from trains and boats and church bells chimed at 9:33 a.m. – the exact time Khomeini's chartered Air France Boeing 747 touched down 40 years ago at Tehran's International Mehrabad airport.

The 10-day anniversary festivities, known as the "Ten Days of Dawn", end on 11 February, the date Shah Mohammad Reza Pahlavi's government collapsed.    (AP)