Japan on Monday mourned those killed in the March 2011 earthquake and tsunami that also caused the nation’s worst nuclear accident.

More than 18,500 people died or went missing in the twin natural disasters in north-eastern Japan, with about 400,000 houses and other buildings destroyed.

Many roads and bridges have since been rebuilt, but more than 300,000 people still live in temporary housing across the country.

Tens of thousands have left the north-eastern region.

Emperor Akihito and Empress Michiko attended a memorial ceremony in Tokyo with Prime Minister Shinzo Abe and relatives of the victims.

“We were deeply moved to see how, in these difficult times, the people, whether in the afflicted regions or in the places where they had evacuated to, were bracing themselves against adversities and carrying on with their lives,” the emperor said.

“We feel, with renewed resolve, that it is important for all of us to continue to watch over these people and to share in their grief as much as possible,” he said.

The emperor also expressed gratitude for international support.

“After the disaster, we received so much goodwill from people around the world who sent us supplies and contributions, and helped us in various ways,” he said.

On Sunday, anti-nuclear rallies were held around Japan with participants demanding the government to scrap all atomic power plants.

Protesters in Tokyo marched on government ministry buildings and the headquarters of Tokyo Electric Power Co, which runs the Fukushima Daiichi nuclear plant.

The plant suffered meltdowns at three of its six reactors after it was hit by the disaster. About 160,000 people have been forced to leave their homes due to fears of radioactive contamination.