A series of earthquakes near the Greek island of Santorini have led authorities to shut down schools, dispatch rescue teams with sniffer dogs and send instructions to residents including a request to drain their swimming pools.

Fresh overnight tremors shook Greece's top tourist island Santorini, media reports said, prompting people to sleep outdoors and others to leave by plane or ferry.

Schools on the Greek island of Santorini have been told to close on Monday in response to an increase in seismic activity in recent days. Authorities have also advised against "large gatherings in enclosed spaces" across the island - a popular tourist destination known for its whitewashed buildings and blue domed churches.