Earlier on Sunday, the US Geological Survey (USGS) issued a tsunami alert, forecasting "hazardous waves" after a 7.4-magnitude quake at 0849 GMT, which was the strongest of a series of earthquakes in the northern Pacific Ocean.

The USGS said it expected waves of between 30 centimetres and one metre (up to 3.3 feet) on Russian coasts, and less than 30 centimetres in Japan and the US state of Hawaii.

"The tsunami threat to populated areas in Kamchatka has passed," said Russia's emergencies ministry a few hours later.

This was also confirmed by local governor Vladimir Solodov, who said that by the estimated arrival time of the first wave, "no tsunami has been observed in any populated areas".

However, he warned of possible aftershocks, which are usual during seismic events and can trigger further earthquakes.

The epicentre of the quakes was in the Pacific Ocean, around 150 kilometres (93 miles) east of the city of Petropavlovsk-Kamchatsky, the USGS said.

The series of aftershocks included a 6.7-magnitude quake, it added.

Russia's emergencies ministry wrote on Telegram that it expected waves of up to 60 centimetres in the Commander Islands in the southwestern part of the Bering Sea, and waves of 15 to 40 centimetres in the Kamchatka peninsula.

The peninsula is the meeting point of the Pacific and North American tectonic plates, making it a seismic hot zone.

Since 1900, seven major earthquakes of magnitude 8.3 or higher have struck the area.