TOKYO - Japan's extended spring holiday period is usually a time for the hardworking nation to relax, spend quality time with family and travel to vacation spots both at home and overseas.

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But with "Golden Week" this year coming less than two months after Japan's worst-ever earthquake and a mammoth tsunami devastated a wide swathe of the northern coast, thousands of Japanese will be spending their days off shovelling mud and clearing wreckage.

The March 11 disasters have left nearly 28,000 dead or missing and touched off a nuclear crisis that forced tens of thousands from their homes.

Many relief workers in the disaster-hit areas, while "extremely grateful" for the help, said they were bracing themselves for the influx.

"It's going to be pretty chaotic," said Susumu Sugawara at the Iwate Disaster Volunteer Centre in Morioka, some 460 km north of Tokyo. At least 3,000 to 5,000 people were expected to help out in Iwate prefecture alone, where some coastal communities were virtually flattened.

"We put up a post on our website offering buses for volunteers starting from May 2nd to the 8th, and all of them were completely full in three hours."

Volunteer work is a legacy of Japan's last major quake in 1995, when more than 1 million people rushed to the western city of Kobe to fill gaps left by a sluggish government response.

But gasoline shortages, transport disruptions and the sheer scale of the destruction this time prompted authorities to stem the influx of well-wishers at first.

Sugawara said his organization, worried about traffic jams and lack of parking, was encouraging volunteers to drive up in groups rather than individually. Places to stay are also limited, so people may have to drive up to two hours between accomodations and the disaster sites.

Student volunteers being sent up in groups on buses from Tokyo by Nippon Zaidan, a non-profit organization, were preparing to be self-sufficient, planning to lay tarpaulins on a gymnasium floor and spend their nights in sleeping bags.

"As much as possible, we want to avoid being disruptive," said Daisuke Nakagawa at Nippon Zaidan, adding that the volunteers will take their own food and gasoline to Ishinomaki, a hard-hit city in Miyagi prefecture, just south of Iwate.

He said that many of the town's elderly population are unable to clear the rubble and they appreciate the young volunteers' help.

Nippon Zaidan hopes to send 10,000 volunteers, both students and adults, to the disaster zone by December.

Other organizations, though, encourage volunteers to stay in local lodging and spend money in local stores where possible, contributing to reconstruction that way.

Although the first few days of the holiday week may be fraught with logistical headaches, Sugawara in Iwate says they need all the help they can get.

"We still desperately need volunteers to help clear the towns, so this is very helpful," he said.