A court in Bangladesh agreed on Monday to put on trial several defendants on murder charges over the collapse of the Rana Plaza which killed 1,135 workers, many of them making garments for Western retailers, a court official said.

Forty-one defendants in total face charges over the April 2013 disaster at the complex, which housed five garment factories supplying global brands. Plaza owner Sohel Rana is the principal accused.

The collapse of Rana Plaza, built on swampy ground outside the capital Dhaka, ranks amongst the world's worst industrial accidents, and sparked an outcry for greater safety in the world's second-largest exporter of ready-made garments.

Rana himself is in jail, while 16 of his co-accused are on bail and the remaining 24 have absconded. The court issued arrest warrants against them on Monday.

Shortly after the collapse a former chief engineer of the state-run Capital Development Authority told Reuters that Rana had not received proper consent for the building, and that an additional three storeys had also been added illegally.

Duty free access offered by Western countries and low wages helped turn Bangladesh's garment exports into a $25 billion a year industry. Sixty percent of the clothes go to Europe, with 23 percent heading to the United States and 5 percent to Canada.

Roy Ramesh Chandra, president of United Federation of Garments Workers said that the trial process has taken a long time. "Still, it is a step forward and we demand justice," he told Reuters.