NAGAOKA, Japan — Rain pelted a weary region recovering from powerful weekend earthquakes, creating fears of mudslides, as 100,000 people took refuge in shelters Monday, too afraid to go home as aftershocks delivered new jolts.

Saturday's magnitude 6.8 earthquake and a series of strong aftershocks killed 26 people, tore up roads, upended homes and derailed a high speed train in rural Niigata prefecture, about 250 kilometres northwest of Tokyo.

A 5.6-magnitude temblor hit just after dawn Monday, swaying buildings and deepening concerns that the area's already shaky infrastructure would sustain more damage. Several smaller aftershocks were felt through the night, and Japan's Meteorological Agency warned of more quakes in the region.

About 100,000 people took refuge at gymnasiums and public buildings. Thousands of others slept in their cars and in tents.

"The aftershocks are still strong, so we felt it was safer to stay here even though our house wasn't all that badly damaged," said Misako Tsubata as she sipped tea outside the tent where she was staying with her two daughters, her mother and her husband.

An 80-year-old man died at a shelter after collapsing from shock, Niigata police reported late Monday, bringing the death toll to 26. Police also said a 39-year old woman and her two young children were missing.

Emergency workers rushed food and blankets to the evacuated, though ripped asphalt and landslides made many roads impassable. Train and bus services to the area remained largely shut down.

About 60 per cent of Niigata's large shelters didn't have enough food while 37 per cent lacked sufficient blankets, public broadcaster NHK reported.

"I've only eaten half a rice ball and half a piece of toast today," an unidentified woman told NHK.

The Japan Red Cross said it was rushing 10,000 blankets to keep victims warm during the night. The national government also planned to ship 10,000 blankets.

A Japanese supermarket chain, Seiyu, said it would donate 20,000 bottles of water, 10,000 towels and 20,000 rolls of toilet paper.

Prime Minister Junichiro Koizumi planned to visit one of the worst-hit towns on Tuesday. "We will to listen carefully to what the situation is in each area and respond to their requests," Koizumi told reporters.

Saturday's quake was the worst to hit Japan since 1995, when more than 6,000 people were killed by a 7.2 magnitude temblor in and around the port city of Kobe.

Utilities gradually restored service, but 47,000 households remained without power Monday evening, said Tohoku Electric. Tens of thousands still lacked water and gas.

Some 400 aftershocks strong enough to be felt were recorded in the two days following the initial up-down jolt. About 2,000 people were reported injured, most of whom had been treated and released by Monday.

The National Police Agency counted 89 landslides and roads sliced in 1,330 places. Destroyed buildings totalled 151 and partially damaged structures reached 2,607, the Fire and Disaster Management Agency said.