Iranians celebrate with a patriotic song

The celebrations began just after 0930 local time, the exact hour that an Air France 747 carrying Ayatollah Khomeini touched down at Tehran airport in 1979. Army helicopters dropped millions of flowers on the route the Ayatollah took through the city.

It was 20 years ago today

Towns and cities throughout Iran have been decked out in coloured lights and there will be 11 days of celebrations to mark the victory of the revolution. There have been firework displays and even a laser show in Tehran.

Iranian television repeatedly showed archive film of the tumultuous scenes which followed the Ayatollah's return.

He made his way through packed streets to the Behesht-e-Zahra Cemetery on the outskirts of Tehran where he made his first speech before taking up leadership of the forces that brought down the Shah's regime.

Charismatic cleric

World Affairs Editor John Simpson: In Tehran 20 years ago

It was there that he was buried 10 years later.

At the memorial ceremony, one of the Ayatollah's close companions, the former president, Hashemi Rafsanjani, paid glowing tribute to the charismatic cleric who provided the focal point for the national uprising against the Shah.

Pictures of Ayatollah Khomeni dominated the TV

As it took 10 days before the government set up by the Shah was overthrown, an 11-day period will be marked by celebrations and events culminating in a big military parade on 11 February.

For all Iranians, this will be an occasion to contemplate the changes that the last 20 years have brought.

But the anniversary comes at a time when there is a power struggle power between reformists and hardline conservatives going on in Iran over which direction the country and the revolution should take in a rapidly changing world.

Explosions cloud mood

Jim Muir in Tehran: "The big unanswered question: where does the revolution go from here"

The BBC's Middle East correspondent, Jim Muir, says that the celebrations are a contrast with the somewhat subdued mood currently prevailing in the country.

On the eve of the anniversary, a number of explosions were reported near the intelligence ministry compound on the outskirts of the capital.

The official Iranian news agency said windows had been broken and several cars damaged in what it described as a failed attack by the People's Mujahadeen, an armed opposition group based in Iraq.

Meanwhile, some agents of the Intelligence Ministry have been arrested for alleged involvement in the recent killings of liberal writers and intellectuals.