A powerful 6.6-magnitude earthquake has stuck off Russia's eastern coast, at the Kamchatka peninsula.

Russian monitoring centres told the TASS news agency tsunamis of about 1.5m were possible, according to RT, though the site said Russia's emergencies ministry later stood down the warning.

The earthquake struck at a depth of 22.8km just after 4am UK time, according to the US Geological Survey.

The United States' tsunami warning centres were not showing a risk of waves to US territories.

The largest city in the area is Petropavlovsk-Kamchatsky, with a population of some 187,000, the USGS said.

The Kamchatka region lies near a subduction zone, where the Pacific plate slides underneath the North American.