Iran is marking the 40th anniversary of the Islamic Revolution that toppled the shah, ending 2,500 years of monarchical rule.

On February 1, 1979, Ayatollah Ruhollah Khomeini returned from France after 14 years in exile to become the supreme leader of the Islamic Republic of Iran.

Across Iran on February 1, sirens blared at 9:33 a.m. – the exact time Khomeini’s plane touched down at Tehran’s international airport 40 years ago.

Known as the Ten Days of Dawn, the anniversary ends on February 11, the date Mohammad Reza Pahlavi’s government collapsed, bringing hard-line Shi’ite clerics to power.

The return of Ayatollah Ruhollah Khomeini to Iran on February 1, 1979, marked a turning point in Iranian history. Millions of followers turned out in Tehran to greet Khomeini as he arrived from Paris, where he had spent 14 years in exile as an outlawed cleric. Iran's ruler at the time, Shah Mohammad Reza Pahlavi, had fled the country two weeks before Khomeini came back. In March, Khomeini led the drafting of a constitution for the renamed Islamic Republic of Iran. He was officially installed as supreme leader after a referendum in November 1979.

Thousands gathered at Khomeini’s mausoleum in Tehran on February 1 as an army band played revolutionary anthems.

Ayatollah Ahmad Jannati 91, head of Iran’s influential Assembly of Experts, criticized those seeking better ties with the United States.

"Curses on the wrong school of thought that thinks we can't run the country unless America helps us," Jannati was quoted as saying by the AFP news agency.

"America's power is on the decline. We should not be afraid of America," Jannati added.

Based on reporting by AFP and AP