Retailers including Tesco, Marks & Spencer and Asda were supplied goods from supply chains that used slaves from the UK’s largest human trafficking network.

Victims of a modern slavery ring that trafficked over 400 people to the UK, many of which were made to work on farms that supplied major supermarkets.

The human trafficking gang brought around 400 vulnerable and homeless people from Poland to the UK with the promise of good money upon arrival. The victims arrived to find their bank accounts controlled as they were paid as little as 50p a day for their manual labour, from which an eight-strong gang earned £2m over five years.

Some of the victims worked packing spring onions at Sandfields Farm, Worcestershire, which is part of a fresh produce group that counts Waitrose, M&S, Sainsbury’s, Tesco and Asda among its customers, The Sunday Times reported.

One worker, named Dariusz, said he was forced to load large crates at the farm that were taken to a warehouse and wrapped in Tesco and Asda branding.

At least 25 other victims were forced to make garden sheds and fences for a Kidderminster firm that supplies retailers including Homebase, Argos and Wickes.

All the retailers and other companies involved said they were not aware that workers had been exploited.

The revelations came as part of an ongoing legal case relating to the largest European human trafficking network brought before the courts, of which two trials are underway in Birmingham.