A massive search and relief operation was under way in northern Iran after two earthquakes killed some 300 people and injured thousands more.

The quakes, measuring 6.4 and 6.3 according to the US Geological Survey that monitors seismic activity worldwide, struck in East Azerbaijan province, on Saturday. Thousands of people have been forced to spend the night in emergency shelters. A series of aftershocks rocked the region on Sunday.

Rescue teams have been using sniffer dogs to search through the rubble.

"Search and rescue operations have ended and we are now working to ensure survivors' needs in terms of shelter and food," Interior Minister Moustafa Mohammad-Najjar told state television.

Reza Sadiqi, the governor of Ahar county in East Azerbaijan province, told semi- official Fars news agency on Sunday that the number of fatalities in the quake stricken regions amounted to 300.

An official from Iran's Red Crescent Society told semi-official ISNA news agency that some 2,600 people were injured.

The Chinese embassy in Iran told China Daily there had been"no reports of Chinese citizens being killed or injured".

"We have not received any calls for help," an embassy spokesman said.

There are nearly 4,000 Chinese citizens in Iran, he said.

Officials said casualty figures are expected to rise, as some of the injured were in critical condition while hundreds were trapped under rubble, inaccessible to rescue workers who were hampered by darkness in the first hours after the quakes.

"I saw some people whose entire home was destroyed, and all their livestock killed," Tahir Sadati, a local photographer said. "People need help, they need warm clothes, more tents, blankets and bread."

The worst damage and most casualties appear to have been in rural villages surrounding the towns of Ahar, Varzaghan and Harees, near the major city of Tabriz, Iranian media reported.

Many villages are hard to reach by road, hindering rescue efforts. Hospitals in Tabriz, Ardabil and other cities nearby took in many of the injured, residents and Iranian media said, and there were long queues of survivors waiting to be treated.

Aidin, a Tabriz resident, said he went to give blood at a local hospital on Saturday and saw staff struggling to cope with the influx of patients. Most patients had been taken there by their families, he said, indicating a shortage of ambulances.

Ahar's 120-bed hospital was full, said Arash, a college student and resident of the town. There were traffic jams on the narrow road between Ahar and Tabriz as victims tried to reach hospitals, he said by telephone.

The quakes cut communications and helicopters had to rush to the scene to gauge the severity of the quakes.

Teheran University's Seismological Center said the first quake struck at 4:53 pm. The second struck just 11 minutes later.

Wang Chenyan in Beijing contributed to the story.

Reuters-Xinhua-AFP