Strong winds and rain flattened thousands of houses

At least 39 people are now said to have died in the storms, which ripped apart houses and caused widespread damage.

Several thousand people were made homeless and have been living outdoors after their houses were blown away by strong winds and rain.

The soldiers will help build homes and shelters for the victims as part of a massive rehabilitation exercise.

Emergency supplies

Army doctors are treating the wounded in the northern districts of Gaibandha and Rangpur amid fears that the toll could rise.

"We are struggling to cope with hundreds of injured persons," Gaibandha district civil surgeon Habibur Rahman is quoted as saying by the AFP news agency.

The disaster management ministry says it has sent emergency food supplies and building materials.

"We are distributing biscuits... and giving tin sheets to the affected families to build homes," Asadul Habib Dulu, Bangladesh's food and disaster management minister, said.

Nearly 3,000 homes were destroyed in the tornadoes which hit the area late on Sunday.

Winds of nearly 100 km/h (60 miles an hour) hit villages after dark, destroying homes made of corrugated iron or mud and straw.

More than 95% homes in some villages were completely destroyed, officials said.

Powerful storms kill hundreds of people annually in Bangladesh, but most take place during the summer monsoon and correspondents say few people would have been prepared for a storm so early in the year.