CHENNAI, India (Thomson Reuters Foundation) - The death of a 21-year-old woman working in a garment factory in south India has reignited concerns among rights campaigners over the working conditions of low-paid textile workers in the multi-billion dollar industry.

The woman from the eastern Indian state of Odisha had a fever for a few days and died on Dec. 14 in a hospital in the garment hub of Tirupur in the southern state of Tamil Nadu.

The cause of her death remains unknown pending results of a post mortem investigation, police said.

A report into the woman’s death by the Rights Education and Development Centre, a charity working with textile workers, said migrant workers “were not being paid minimum wages and were unregistered”.

There is a growing concern over the number of migrant workers coming to work in south India’s textile hub, spending up to 14 hours spinning yarn and stitching garments for global brands.

Drawn from poor families in eastern India, the workers can be confined to factory premises, paid poorly and unaccounted for in the workforce, campaigners said.

“We are demanding a probe into the case to ensure justice for the young girl who died and other migrant workers working in the mill,” said Karuppusamy Raman, part of the fact finding team.

“The condition of migrant workers is appalling. We were told that they are living in cramped hostels, completely isolated. They are being brought here through agents and we suspect cases of trafficking as well.”

Civil society groups have been calling for proper registration of migrant workers, highlighting the fact many of these workers are isolated and garment manufacturers are not transparent on the terms under which they are hired.

There are more than 1,500 mills in Tamil Nadu, the biggest hub for textile and manufacturers in India, employing up to 400,000 workers to turn cotton into yarn, fabric and clothes.

But as growing number of educated youngsters in the southern state refuse exploitative work conditions, migrant workers are increasingly being hired and form more than 20 percent of the workforce today.

“Thousands of workers arrive at the station here and after a few hours disappear into factories. There is no record of who came and where they have been employed,” Sekar Nataraj of a knitwear labor union told the Thomson Reuters Foundation.

Campaigners say it is difficult to protect the rights of these workers because of lack of access to the factory hostels.

“As mandated by law, there has to be a list of workers and companies must be forced to comply,” Nataraj said.