Casualties are reported to be particularly high in the town of Ercis, close to the Iranian border, where dozens of buildings fell.

Reports spoke of thousands of residents running screaming in the streets.

Fears rose of a death toll in the hundreds as rescuers worked into the night to find survivors.

The earthquake struck at 13:41 (10:41 GMT) at a depth of 20km (12.4 miles), with its epicentre 16km north-east of Van in eastern Turkey, the US Geological Survey said.

It was followed by a series of powerful aftershocks, also centred north of Van, including two of magnitude 5.6 soon after the quake and one of 6.0 late on October 23.

Prime Minister Recep Tayyip Erdogan, who is visiting the Van region, said 138 people had been killed, 45 of them in the town of Ercis and 93 in Van.

He said about another 350 people had been injured, but other officials gave higher casualty figures.

Up to 80 buildings, including a dormitory, collapsed in the town about 60km north of Van, while 10 fell in Van itself.