The charges would be pressed against 41 people including building owner Sohel Rana, his parents and more than a dozen government officials.

"It was a mass killing. All 41 of those charged have a collective responsibility for the tragedy," lead investigator Bijoy Krishna Kar told news agency AFP, adding that all of them could be sentenced to death if convicted of murder.

The Rana Plaza building collapse in April 2013 killed 1,137 people, many of them garment workers making clothes for Western retailers. Initially investigators had signaled the accused would be charged with culpable homicide but shifted to murder charges after investigators found the workers had been told to enter the building on the day of the collapse, despite not wanting to because the building had developed cracks the day before.

The sudden collapse in April 2013 killed and injured thousands of people

"They [Rana and the factory owners] discussed and decided to keep the factory open. They sent the workers to their deaths with cool heads," Kar said.

Illegal building

Some of the accused could also face charges of violating building safety rules when additional floors were added to the original building. It was supposed to have been used as a shopping mall but the illegally-built upper floors were transformed into factories.

Also among those charged are the owners of the garment factories, three government engineers who approved the building extensions, plus the mayor of Savar and a local councilor who are accused of ignoring building and factory laws.

The disaster brought global attention to the grim conditions in Bangladesh's garment industry, where low wages attract global brands, earning the country more than $20 billion (18 billion euros) annually in exports. Italy's Benetton, Spain's Mango and British chain Primark all had clothing made at the factory.

se/msh (AP, AFP)