Japanese officials raised the estimated death toll from the earthquake and tsunami that devastated the country's northeast to more than 10,000 Sunday, as hundreds of thousands of survivors salvaged what belongings they could and sought food and water at emergency centres.

Friday's quake and tsunami damaged key nuclear plants and left entire cities demolished in their wake. Police in the northeastern Miyagi prefecture, one of the worst affected by the disaster, estimated Sunday that more than 10,000 people had been killed in the region, which is home to about 2.3 million people. So far, the number of confirmed dead is 1,800, which includes about 200 bodies that were found along the coast on Sunday. But thousands more are still missing.

Hundreds of thousands of survivors have sought refuge at emergency centres, which quickly ran low on food, water and other supplies. An estimated 1.4 million households were still without water Sunday, and at least 1.9 million homes did not have electricity.

The Japanese government doubled the number of troops dedicated to rescue and recovery operations from 51,000 to about 100,000, and ramped up the shipment of supplies to the affected areas. Aid included 120,000 blankets, 120,000 bottles of water and 110,000 litres of gasoline, as well as food.

Rescue teams from Germany, the U.K., China and the U.S. have arrived, while two U.S. aircraft carriers are set to begin operations in the affected region. Rescue crews have been searching for missing people along hundreds of kilometres of the Japanese coast.

Japanese Prime Minister Naoto Kan announced Sunday that the capital and other major cities will suffer rolling blackouts starting on Monday as Tokyo's electric company rations power.

Tokyo Electric announced on Sunday that it will begin rolling blackouts in three hour windows to help make up for a severe power shortfall. Officials say 25 per cent of the country's capacity has been removed from the system.

Kan called the disaster the worst crisis since World War II, and appealed in a television address for the Japanese people to come together to rebuild.

"This is Japan's most severe crisis since the war ended 65 years ago," Kan said.

Pope Benedict praised the "dignity and courage" of the Japanese people in coping with the tragedy. In a Sunday blessing, the Pope encouraged aid workers to help those still reeling from the disaster.

Meanwhile, Japan's Meteorological Agency upgraded the magnitude of Friday's quake to 9.0 after analyzing seismic waves. The agency earlier measured it at 8.8 magnitude quake.

The quake was the biggest to hit Japan since record-keeping began in the late 1800s. The agency warned Sunday of more strong aftershocks after Friday's quake, which unleashed massive tsunamis.

The U.S. Geological Survey has measured the quake at magnitude 8.9. The agency's estimate remained unchanged Sunday.

Meanwhile, strong aftershocks continued Sunday, including one with a magnitude of 6.2 that originated in the sea, about 179 kilometres east of Tokyo.

Communities survey ‘so much destruction'

While the official death toll may not be known for days, or weeks, CTV's Tom Walters, speaking from Narita, Japan, said locals on the ground have little doubt that the death toll is much higher than the estimates being released by officials.

"There really is so much destruction, so many areas of debris that are difficult to search, so many areas were we are told rescuers have yet to reach," Walters told CTV News Channel on Sunday. "I don't think there is any confidence here on a full accounting for the human toll of this disaster."

In the town of Minamisanrikucho, about 10,000 people, or two-thirds of the population, have not been heard from since the tsunami buried the town. Images shown on state broadcaster NHK showed only a handful of tall structures still standing in the town, including the local hospital.

In the port city of Sendai, firefighters sifted through the rubble, recovering bodies. Survivors in the town sought shelter in local community centres, schools and at city hall.

Outside the city, a large refinery remained on fire, with 30-metre flames shooting into the air. Plumes of smoke hovered over the town.