An earthquake that struck Friday off north-eastern Japan caused extensive damage, Prime Minister Naoto Kan said while urging the public to remain calm, DPA reported.
Japan's Meteorological Agency measured the quake at a magnitude of 8.8 while the US Geological Survey said is was 8.9. The agency said the quake was Japan's strongest on record.
Kan said the government set up a task force to deal with the aftermath of the quake and said no nuclear reactors leaked radiation.
Japan had received offers of aid from other countries, Chief Cabinet Secretary Yukio Edano said.