More than 1,400 people have been killed and thousands more injured in a catastrophic 7.8-magnitude earthquake that rocked Turkey and Syria overnight, flattening entire neighbourhoods while many families were still asleep.

Tremors from the deadly quake - which lasted about a minute and could be Turkey's largest ever - were felt as far away as Egypt, Lebanon and the island of Cyprus, while a tsunami warning was briefly issued by authorities in Italy along the country's coast.

Residents were jolted awake and fled from their homes in terror into the cold, rainy and snowy night across southeast Turkey and northern Syria, taking shelter in cars from a wave of at least 40 aftershocks and collapsing buildings.