THE world was responding to Iran's plea for help last night after an earthquake devastated an historic city, killing up to 20,000 people.

Survivors and rescue teams were struggling in sub zero temperatures to find anyone still alive under the rubble that was - until the early hours - the bustling city of Bam.

Rescue organisations and aid teams from around the world - including Britain - were preparing to help the stricken country last night.

Official figures said 6,000 people were killed and 30,000 injured - most of them critically - in the south-eastern city. But Iranian MP Hasan Khoshrou said that 10,000 had been killed, and others doubled the figure.

He said people at the scene had told him the devastation was "beyond imagination".

The Iranian government said 70 per cent of houses in the city of 80,000 people had been destroyed. Thousands were left homeless and were spending the night in the open in freezing weather.

The 6.3 magnitude quake hit Bam, 630 miles from the capital Tehran, in the early hours.

"The quake hit the city when most of the people were in bed, raising fears that the death toll may go higher," said Mr Khoshrou.

Hardly a building remained standing in the old quarter of Bam.

In one street, only one wall and some trees were standing. People were carrying away the injured, while others sat sobbing next to the corpses of their loved ones.

Mohammed Karimi, in his 30s, lost his wife and four-year-old daughter.

"This is the day of resurrection - there is nothing but devastation and debris," he said as he held his dead daughter in his arms.

President Mohammad Khatami attended an emergency meeting and urged the entire country to help the victims of the quake. He declared three days of mourning for what he called a "national tragedy".

The government told the UN it needed medicines, tents and generators.

Because hospitals in the area had been destroyed, the government sent transport planes to evacuate the wounded for treatment elsewhere.

Interior Minister Abdolvahed Mousavi Lari said 70 per cent of residential Bam had been destroyed and there was no electricity.

"Our immediate two priorities are dealing with the people who are trapped and transferring the wounded to other areas," he said.

He said four C-130 Hercules transport planes had ferried wounded out of the area. Setting up tents was a priority because of the cold. Night-time temperatures were expected to drop to -6C (21F).

Hardly any buildings in Iran are built to withstand earthquakes, although the country sits on several major fault lines and tremors are frequent.