A powerful earthquake has struck off Turkey's Aegean coast, north of the Greek island of Samos.

The 7.0 magnitude tremor was centred off Turkey's Izmir province, the US Geological Survey said.

Turkey put the magnitude of the quake at 6.6, saying four people had died and 120 were injured in the city of Izmir. About 20 buildings collapsed.

The shallow tremor is reported to have triggered a mini-tsunami that flooded Izmir and the Greek port of Samos.

The USGS said the quake - which was felt as far away as Athens and Istanbul - struck at a depth of 10km (six miles), although Turkish officials said it was 16km below ground.

Turkey and Greece both sit on fault lines and earthquakes are common.

In Izmir, Turkey's third largest city, many people were seen running out into the streets in panic and fear after the quake struck.

Videos have been posted on social media appearing to show the moment when one multi-storey building collapsed, the BBC's Orla Guerin in Istanbul reports. Other footage shows local people scrambling over rubble looking for survivors.

There are reports of flooding in the city after the sea level rose, and some fishermen are said to be missing.

Significant damages has been recorded on the island of Samos after the 6.7 magnitude earthquake that occurred at noon in the sea area northwest of the island.

The Minister of Development, Adonis Georgiadis, also spoke about extensive damage to buildings during his first briefing in Parliament.

According to samos24.gr, part of the church of Panagia Theotokou in Karlovasi has collapsed.

Tsunami hits Greek island of Samos after 7.0 magnitude earthquake video:

Islanders were urged to stay away from coastal areas.

Reports said Friday's quake was also felt on the Greek island of Crete.