BAM, Iran (Reuters) - Survivors of an earthquake that devastated Iran's ancient Silk Road city of Bam, killing more than 20,000 people, dug frantically with bare hands through the night early on Saturday for anyone buried alive.

President Bush, who once branded Iran part of an "axis of evil" for allegedly developing weapons of mass destruction, and other world leaders rushed to offer whatever help they could to the Islamic Republic.

The pre-dawn quake on Friday also injured some 50,000 people, government officials said. It measured 6.3 on the Richter scale and struck when most people were still asleep in their homes.

About 70 per cent of Bam, a popular tourist spot some 600 miles southeast of the capital Tehran with an historic citadel and other centuries-old buildings, was leveled.

Reuters witnesses in Bam said hundreds of corpses were bundled into trucks and the back seats of cars. Distraught relatives wailed next to bodies wrapped in blankets.

Many residents were feared trapped under the rubble and the city of 200,000 in Iran's Kerman province was without water, power or fuel as night temperatures headed below freezing. Some people accused the government of doing nothing to help them.

DEATH TOLL MOUNTS

"The (death toll) is now more than 20,000," said a senior government official, as survivors lit fires to stay warm in the open amid the mass of flattened mud-brick houses.

"I have lost all my family. My parents, my grandmother and two sisters are under the rubble," said Maryam, 17.

One grief-stricken old woman, her face covered with dirt, just kept saying: "My child, my child."

Washington has no official ties with Tehran, but Bush said in a statement: "We stand ready to help the people of Iran."

A spokesman for Bush said Washington would be offering humanitarian aid, and a U.S. official said the State Department would be announcing an aid package soon.

The United Nations, European Union countries, Russia, Poland, Japan, Turkey and others also heeded Iran's appeals for help from the international community. They pledged doctors, medical supplies and rescuers with sniffer dogs and special equipment to locate survivors.

Russia ordered medical rapid-response units and dog-handlers to seek those trapped. Germany was flying in blankets and winter coats for those huddled in the bitter cold.

"We need help, otherwise we will be pulling corpses, not the injured, out of the rubble," Brigadier Mohammadi, commander of the army in southeast Iran, told state television.

INJURED TREATED AMID RUBBLE

Rubble-strewn pavements were lined with injured, some on intravenous drips.

State media said two hospitals had collapsed, crushing many of the staff, and remaining hospitals were full. The injured were being ferried to neighboring towns.

Mechanized diggers hollowed out trenches where the dead were hastily buried without rites.

A large part of the ancient citadel was destroyed, Kerman province governor Mohammad Ali Karimi said. Dating back 2,000 years, it had sprawling fortifications, towers, buildings, stables and a mosque. It was the city's main tourist attraction.

"The city of Bam must be built from scratch," said its governor Ali Shafiee.

Houses in the date-growing area are traditionally made from mud-brick, making them vulnerable to earthquakes.

Bam is on the old Silk Road route between China and Europe used by merchants and travelers for centuries. It is a tourist spot with inns, a theological school and bazaars.

In Tehran, state television showed people queuing to give blood. Bakeries in Shiraz said they would make bread from dusk until dawn as their contribution to the aid effort.

Quakes are a regular occurrence in Iran, an oil-producing country crossed by major faultlines in the earth's structure.

In June last year, a tremor measuring 6.3 on the Richter scale hit northern Iran, killing at least 229 people and injuring more than 1,000.