Rescue officials in Bangladesh said they are unlikely to find more survivors in the rubble of a factory that collapsed last week.

Hundreds of garment workers were buried in the rubble in the country's worst industrial accident.

Heavy cranes are being used to lift huge concrete blocks from the wreckage of Rana Plaza, where 381 people are now confirmed to have been killed, according to the latest official toll.

The building housed factories making clothes for Western brands.

Hundreds more of the mostly female workers who are thought to have been inside the building when it caved in last Wednesday remain unaccounted for.

A fire overnight further hampered the last desperate efforts to find survivors.

"We are giving the highest priority to saving people, but there is little hope of finding anyone alive," army spokesman Shahinul Islam told reporters at the site.

As anger continued to mount over the disaster, the owner of the building was arrested by police yesterday.

Police said he had been trying to flee to India.

About 2,500 people have been rescued from the wrecked building in the commercial suburb of Savar, about 30km from the capital, Dhaka.

Last night, sparks from rescuers' cutting equipment started a fire in the debris as they raced to save a woman who may have been the last survivor in the rubble.

Retailer Primark has said it is to pay compensation to victims of the disaster, including long-term aid for children who have lost parents.

It said it will also provide financial aid to the injured and payments for families of those who died.

The retailer said it has a team in Bangladesh working with a local NGO to address the immediate needs of victims.