A magnitude 7.8 earthquake has knocked down multiple buildings in southeast Turkey and northern Syria, killing more than 500 people as they slept and trapping many others.

Tremor struck at 04:17a.m local time (01:17 GMT) at a depth of 17.9km (11 miles). The tremor was also felt in Lebanon, Cyprus and Egypt. There were at least six strong aftershocks.

There are fears the number of deaths will rise sharply in the coming hours.

Many buildings have collapsed and rescue teams have been deployed to search for survivors under huge piles of rubble.

So far reports indicate that thousands have been injured. Rescue workers and residents frantically searched for survivors under the rubble of buildings in multiple cities on both sides of the border.

Turkey lies in one of the world's most active earthquake zones.

In 1999, more than 17,000 people were killed after a powerful tremor rocked the north-west of the country.