Textile and garment firms in southern India who supply dozens of major European and US brands and retailers, including Marks & Spencer, Mothercare and supermarket giant Tesco, are accused of selling clothing made by girls working in slave labour conditions.

The claims are made by lobby group Anti-Slavery International and Dutch campaign group SOMO in a report called 'Slavery on the high street.' The allegations are based on interviews with over 200 former workers in cotton spinning mills and factories around Tirupur in western Tamil Nadu.

The research is said to have found five Indian clothing makers - SP Apparel, Bannari Amman, SCM, Eastman and Prem Group - forced young women and girls to work 12-16 hours a day in prison-like conditions, many for well below the minimum wage. The workers were also confined to the factory or mill even on rest days.

Export data from two Indian ports confirms dozens of major European and US brands purchase garments from these companies, Anti-Slavery International said.

The workers are promised a lump sum 'bonus' payment at the end of their three-year contract, but this is almost never paid - either because the worker is unable to finish the contract because of ill health or because management finds a reason to cancel the contract.

The report also says the Indian manufacturers recruit unmarried girls and women from poor 'lower' caste families, and exploit local marriage practices by offering a lump sum that could be used to pay for the worker's marriage dowry.

The campaigners are calling on the brands implicated in the research take action to end slavery in their supply chains.

They say earlier attempts at the end of 2010 failed to secure a joint commitment to eradicate the practice, with company-only pledges in May 2011 "lacking any detail to tackle the problem."

In March this year, a multi-stakeholder group conference in Tirupur brought Indian companies, international brands and some workers together to discuss issues relating to forced labour in the garment industry.

Here it was recognised that abuse of the Indian Apprentice Act was a core factor in the forced labour of girls and young women - and at a follow-up meeting in London last month some companies committed to undertake a plan of action to reduce the abuses.