More than 500 people have been killed in a strong earthquake which hit north-west Iran on Saturday, reducing several villages to rubble.

The official Irna news agency said a further 2,000 people had been injured and 25,000 left homeless.

The chair I was sitting on started to whirl around Mary Partovi, Tehran

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The quake, which measured 6.0 on the Richter scale, struck a string of around 52 villages in rugged hill country between the cities of Qazvin and Hamadan.

As rescue workers flooded into the area, hospitals in the nearby cities were swamped with casualties.

More than 1,000 people were in hospital in Qazvin alone.

Most of the deaths occurred in the town of Bou'in-Zahra, the epicentre of the quake, Red Crescent officials said.

Bou'in-Zahra is 60 kilometres (37 miles) southwest of Qazvin city, the provincial capital.

The tremor was felt 130 kilometres (80 miles) away in the capital Tehran.

Iran is one of the most quake-prone regions in the world, with small tremors occurring almost daily.

Eight provinces hit

The quake hit Bou'in-Zahra at 07:28 am (0258 GMT), followed by an aftershock measuring 4.8 at 08:01 am (0331 GMT).

Eight provinces were shaken by the quake, in both the north and west of the country, state television said.

Officials warned that aftershocks might continue for another two weeks.

Major earthquakes in Iran

1997: More than 1,000 dead in a quake in northwest Iran. Another 1,500 killed in the east three months later 1990: More than 35,000 dead in the northern province of Gilan 1981: 1,000 dead in Kerman province

Most houses are single-storey buildings made of mud brick, which experts say do not stand up well to earthquakes.

"Usually with this kind of building we lose a lot of people," said Professor Fariborz Nateghi, a government advisor on earthquake engineering.

"You lose the walls and the ceiling collapses. They are major killers."

Among the first countries to offer help were Russia and the UK.