At least 378 people were killed in the massive 8.9-magnitude earthquake and tsunami that hit Japan on Friday, but Kyodo News agency said that it estimated that more than 1,000 people died.
The Kyodo report came as grim updates indicating appalling loss of life kept emerging from along the hard-hit east coast of northern Honshu island, where the monster waves destroyed more than 3,000 homes.
The National Police Agency said 178 people had been confirmed dead and 584 missing, with 947 injured in the massive quake and tsunami disaster that devastated large parts of northern Japan's Pacific coast.
Police in Sendai, Miyagi prefecture, separately said 200 to 300 bodies had been found on the shore.
Fears rose for greater losses as reports came in of a ship with 100 people swept away, several trains missing, and a dam break flooding more homes.
The defence ministry said about 1,800 homes in Minamisoma, Fukushima prefecture, were destroyed, while in Sendai authorities said 1,200 houses were toppled by the tsunami.
The small town of Ofunato further north reported 300 houses collapsed or swept away.
More than 80 fires blazed in and around Tokyo and in the Iwate, Miyagi, Akita and Fukushima prefectures, Kyodo reported, quoting Japan's Fire and Disaster Management Agency.
The monster quake was the strongest recorded in the seismically unstable archipelago, located on the "Pacific Rim of Fire".