More than 600 are confirmed dead but Japan is bracing itself for a final death toll of more than 1,000.

''I hope we can overcome this unprecedented national crisis by the power of each individual and the government as well as relevant institutions," Prime Minister Naoto Kan said Saturday, as reported by the local news agency.

Buildings were flattened and trains, cars, crops and homes washed away by a massive 23-foot tsunami, triggered after a magnitude-8.9 earthquake struck near to the east coast of Japan on Friday.

The quake was the largest in Japan's history and reportedly the fifth most powerful quake to hit the world since 1900.

The Archbishop of Canterbury, Dr Rowan Williams, has offered prayers for the people of Japan.

He said: “The news of the horrific earthquake in Japan has shocked us all.

“We await further and more detailed news with apprehension, but I want to say immediately that our hearts and our prayers go out to all who have been affected and that we as a church will do what we can to offer practical as well as spiritual support at this time of great suffering and great anxiety for so many.”

The Salvation Army has dispatched teams to the disaster zone where it is distributing basic necessities to survivors and assessing the scale of the damage.

"We combat natural disasters with acts of God," the group, which has been operating in Japan since 1895, stated. "We are a part of Japan's communities and dedicated to their recovery."

Caritas Internationalis and World Vision are also mobilising their response.

Catholic aid agency Caritas Internationalis is planning its response, although this has been severely hampered by the damage to phone lines.

“Our solidarity is with our brothers and sisters at Caritas Japan and all the Japanese people,” said Lesley-Anne Knight, Secretary General of Caritas Internationalis.

“We will continue to support them at this difficult time and we will keep all of those affected by the earthquake in our prayers.”

Although earthquakes are common in Japan, the scale of the destruction caused by this quake has been particularly severe.

World Vision said its Global Rapid Response Team was on standby for deployment to affected areas.

Geoff Shepherd, World Vision’s humanitarian and emergency affairs director for the Asia-Pacific region, said: “Our staff are prepared to respond.”