Live updates as 6.7 magnitude quake strikes between resorts of Bodrum and Kos
Pictures from the scene show damage to buildings and, in some coastal areas, flooding after sea levels rose in the wake of the mainshock.
The quake has affected an area popular with tourists from many countries.
The UK foreign office has warned of travellers to be careful of aftershocks. A spokesman said:
We are speaking to the Turkish and Greek authorities following an earthquake off the coast of Bodrum and near the island of Kos.
Any British people in the areas affected should follow the instructions of local authorities.