Poor weather hampered relief efforts in northern Japan on Wednesday, adding to woes brought by last week's earthquake and tsunami amid fears of further radiation releases at Fukushima's nuclear reactors.

Slowed by rain, wet snow and cold, rescuers continued the grim task of digging out bodies in the dwindling hope of finding survivors.

Speaking from Tono, about 270 kilometres north of Fukushima and 30 kilometres inland from the coast, Patrick Fuller of the International Red Cross said he had observed a scene of utter devastation where the tsunami first came ashore.

'We are providing about three litres of water per person. We hope it lasts long enough.'— Sendai man helping to fill containers

"Debris, mangled wreckage everywhere, and the survivors are having a tough time being housed in evacuation centres where the Red Cross is supporting them," he told the CBC's Nancy Wilson.

In Sendai, where the temperature was forecast to fall to –3 C Wednesday night,  people were lining up for rations of fresh water from a tanker.

"We are providing about three litres of water per person," said a man, quoted by Reuters, who was helping to fill the survivors' containers. "We hope it lasts long enough."

Water shortages may increase, as communication lines are still down in some of the devastated areas, national broadcaster NHK reported. The Japanese Health Ministry dispatched 309 water trucks to areas where large numbers of people are without water.

NHK has been offering tips to people on how to stay warm by wrapping up in newspapers and cling-film and how to boil water using empty food cans and candles.

In all, an estimated 450,000 people were staying in temporary shelters, often sleeping on the floor of school gymnasiums.

In Minamisanriku, almost half the population of 17,000 is unaccounted for, Reuters reported. The city of Rikuzentakata was almost wiped out by the 9.0-magnitude earthquake and tsunami that followed, the fire department said. More than 80 per cent of the city was flooded.

At Minamisanriku, the Daoji Buddhist temple survived destruction all around it and was offering help to about  30 survivors.

Power shortages

In Tokyo's Shibuya shopping district, the normally bustling streets were unusually quiet Wednesday, CBC's Peter Armstrong said.

"Most people are staying home, giant TV screens over the main square are turned off and most of the huge electric and neon signs have been shut down to conserve energy," Armstrong said.

Rolling blackouts are an issue in many areas of Japan, as authorities try to deal with a power shortfall.

"There's a constant threat of power outages on top of everything else," CBC's Sasa Petricic said from Sagae in northern Japan. "In some cases, they have happened, and in other cases they get cancelled and moved to another time — so an extra level of unpredictability to life."

The official death toll rose above 4,300 on Wednesday, but it is expected to continue climbing above 10,000, with nearly 8,000 people still listed as missing.

In a rare public appearance on national television Wednesday, Emperor Akihito expressed his sympathy and concern for the Japanese people.

"I am deeply sorry for the devastation in the disaster-stricken area," he said in a videotaped statement.

"The number of victims has increased each day and nobody knows how many people will die. I fervently hope we can save as many survivors as possible."

The Red Cross's Fuller said there were thousands of people, many of them elderly, in public buildings such as schools and gymnasiums, lying on the floor or mattresses.

"There is an aging population on this coastline," he told CBC News, "and 75 per cent were old people over 60, so the … Japanese Red Cross has over 80 medical teams going around the areas every day, running clinics in the centres, treating people.

"[The elderly have] conditions people have to be treated for on a day-to-day basis like hypertension and diabetes, and they're suffering, really suffering, and these teams are doing a phenomenal job."