ISTANBUL:A strong earthquake struck the Aegean Sea on Friday and was felt in both Greece and Turkey, where some buildings collapsed in the coastal province of Izmir, authorities said.

People flooded onto the streets in the tourist city of Izmir, witnesses said, after the quake struck the region with a magnitude of up to 7.0.

Turkish Interior Minister Suleyman Soylu said on Twitter that six buildings had collapsed in two districts of Izmir province.

He said there were no reports of casualties from six other provinces where the earthquake was felt but said there were small cracks in some buildings.

Turkey's Disaster and Emergency Management Presidency (AFAD)put the magnitude of the earthquake at 6.6, while the U.S. Geological Survey said it was 7.0. It struck at around 1150 GMT and was felt along Turkey's Aegean coast and the northwestern Marmara region, media said.

The epicentre was some 17 km (11 miles) off the coast of the Izmir province, at a depth of 16 km, AFAD said. The U.S. Geological Survey said the depth was 10 km and that the epicentre was 33.5 km off Turkey's coast.

Residents of the Greek island of Samos, which has a population of about 45,000, were urged to stay away from coastal areas, Eftyhmios Lekkas, head of Greece's organisation for anti-seismic planning, told Greece's Skai TV.

"It was a very big earthquake, it's difficult to have a bigger one," said Lekkas.

High tidal wave warnings were in place in Samos.

Ali Yerlikaya, the governor of Istanbul, where the quake was also felt, said there were no negative reports.