Tesco is facing a landmark lawsuit over allegations that migrant workers were forced to work 99-hour weeks on illegally low pay.

A group of 130 former employees at VK Garment Factory in Thailand are suing Tesco and auditing specialists Intertek for “alleged negligence and unjust enrichment”.

The allegations, which were first reported following an investigation by The Guardian, were made by workers who produced jeans, denim jackets and other F&F clothing for adults and children for the Thai branch of Tesco’s business between 2017 and 2020.

Tesco completed the sale of its Thailand and Malaysia business in December 2020 for around £8 billion.

VK Garment Factory is in Mae Sot, a city near the Myanmar border, which developed a workforce of predominantly Burmese migrant workers.

The employees have already pursued a claim in Thailand against the factory.

In the UK legal case, led by law firm Leigh Day, it is claimed that the migrants were paid at most around £4 a day, working seven days a week, and were “trapped in a cycle of forced labour”. The employees claim they had to work from 8am to 11pm Monday to Saturday, and on Sundays were permitted to finish work at 5pm unless orders meant they had to work longer.

The legal claim said that, despite both Tesco and Intertek carrying out audits at the factory, the unlawful activities that are reported to have been taking place were not identified.

Tesco was not involved in the day-to-day running of the factory but the supply chain workers are nevertheless bringing the case directly against the business.