The Prime Minister said Britain stands “ready to support Japan” after it was struck by a series of major earthquakes on Monday.

Rishi Sunak, who visited Japan in May for the G7 leaders’ meeting, said his thoughts were “with all those affected” and urged Britons in the earthquake-hit areas to follow advice given by Japanese authorities.

The comments came shortly after US President Joe Biden said his administration was in touch with officials in Tokyo and “ready to provide any necessary assistance for the Japanese people”.

The quakes, the largest of which had a magnitude of 7.6, started a fire and collapsed buildings on the west coast of Japan’s main island, Honshu.

It was unclear how many people might have been killed or injured.

In a statement on Monday, Mr Sunak said: “My thoughts are with all those affected by the earthquakes in Japan which have caused such terrible damage.

“Prime minister Fumio Kishida is a great friend of the UK and we stand ready to support Japan and are monitoring developments closely.

“British nationals in the affected areas should follow the advice of the Japanese authorities.”

The Japan Meteorological Agency reported more than a dozen quakes in the Sea of Japan off the coast of Ishikawa and nearby prefectures shortly after 4pm – 7am UK time.

The highest-level tsunami alert was initially issued but it was later dropped several hours later to a regular tsunami.

Even at that level, the sea could still generate waves of up to three metres in height.

Aftershocks could also hit the same area over the next few days, the Far East nation’s meteorological agency said.

Residents in coastal areas have been told not to return to their homes as there could still be deadly waves, with about 30,000 homes said to be without power.

Japanese media footage showed people running through the streets, and red smoke spewing from a fire in a residential neighbourhood.

Photos showed a crowd of people, including a woman with a baby on her back, standing by huge cracks that had ripped through the pavement.

Japan is an extremely quake-prone nation, but a tsunami warning of the magnitude of Monday’s had not been issued since a major quake and tsunami caused meltdowns at a nuclear plant in March 2011.

The UK has been forging stronger ties with Tokyo in recent months, with Mr Sunak and his counterpart signing a defence pact in January 2023 during Mr Kishida’s trip to London.

The pair then signed another deal while Mr Sunak was in Hiroshima for the G7, with the leaders agreeing to closer link their nations on defence, security and cyber matters.

Japan is also part of a trilateral partnership with Britain and Italy, starting work on building the next generation of fighter jets, with the Global Combat Air Programme seeking to deliver a plane that can succeed the RAF Typhoon by 2035.