Grieving women wailed over the bodies of dead relatives as men armed with shovels dug frantically for missing loved ones Sunday, after twin earthquakes killed at least 250 people in northwestern Iran.

AFP journalists in the disaster zone, northeast of the city of Tabriz, saw rescuers working desperately in the rubble of shattered villages where the mud-brick and concrete dwellings had collapsed in the powerful temblors that struck on Saturday.

The bodies, many of women and children, were grouped together out in the open.

Teams of men took turns to dig graves while others boiled water for the ritual cleaning of the dead.

Every now and then, the earth trembled again from one of the scores of aftershocks that jarred the nerves of survivors and exhausted emergency workers who had worked through the night.

The quakes came within 11 minutes of each other on Saturday afternoon as many in the region were at home observing the daytime Ramadan fast.

The U.S. Geological Survey, which monitors seismic activity worldwide, ranked them at 6.4 and 6.3 on the moment magnitude scale, respectively.

"I was working on my farm, on my tractor, and I felt the earth shake and I was thrown off the vehicle," a 40-year-old farmer in one hamlet, Qanbar Mehdizade, told AFP.

"Thank God I was working on the farm with my family," all of whom survived, he said.

In other villages, some were not so lucky. Zeinab, a 13-year-old girl, told how her 16-year-old sister and eight-year-old brother were among the six who died when the quakes hit her village of Mirza Ali Kandi.

The epicenters of the earthquakes were 10 kilometers underground some 60 kilometers northeast of Tabriz, close to the towns of Ahar and Varzaqan.

While Tabriz and the towns, with their more solid buildings, escaped with mostly minor damage, many outlying villages were devastated, half a dozen of them completely flattened.

"The number of dead has reached 250 and the number of injured has topped 2,000," Khalil Saie, the head of the regional natural disasters centre, was quoted as saying by the ISNA news agency.

Earlier he had said that "all the deaths come from rural areas."

Another official at the centre, Morteza Akbarpour, told the Fars news agency that, of the 537 villages in the affected zone, "at least 100 have suffered damage."

The population in the disaster zone was 128,500, he said.

A worker for Iran's Red Crescent, a man in his late 20s who declined to be named, told AFP in one village that authorities were sending more emergency teams from different regions of Iran "because the magnitude of the disaster is so huge."

The Red Crescent took over a sports stadium to shelter the 16,000 people left homeless or too afraid to go back indoors, the Fars news agency reported.

It also provided 3,000 tents, blankets and tones of food -- all a sign of years of preparedness in a nation prone to sometimes catastrophic seismic activity.

President Mahmoud Ahmadinejad's office posted a statement on its website expressing condolences to those in the disaster zone and calling on authorities to "mobilize all efforts to help the affected populations."

The disaster zone was located around 90 kilometers from the borders with Armenia and Azerbaijan, and around 190 kilometers from the border with Turkey.

Iran sits astride several major fault lines and is prone to frequent earthquakes, some of which have been devastating.

The deadliest was a 6.6-magnitude quake which struck the southeastern city of Bam in December 2003, killing 31,000 people -- about a quarter of the population -- and destroying the city's ancient mud-built citadel. (AFP)