Primark and Mothercare have launched inquiries into allegations that factory workers who make their clothes in India are being severely underpaid.

Workers in Bangalore are being paid as low as 13p per hour for a 48-hour week, so little that workers claim they sometimes rely on government food parcels, according to an investigation by the Guardian.

It follows reports by the newspaper in July accusing Primark, Asda and Tesco of breaching international labour standards in Bangladesh.

Gokaldas Export, India’s largest ready-made clothing supplier, which supplies retailers including Marks & Spencer, Mothercare and H&M, has said wages are as low as£1.13 for a nine-hour day, a figure which fails to meet basic needs according to factory workers and Indian unions.

The figure falls below the minimum international labour standards promised by the Ethical Trading Initiative (ETI) in its code of conduct setting out basic rights for employees across the supply chain. M&S, Mothercare, Gap and Primark are members of the ETI.

Workers for factories owned by exporters who supply to Gap, Matalan and Primark were paid similar wages or were regularly forced to work overtime of between six and 18 hours per week, according to reports.

ETI guidelines state that workers should not regularly work more than 48 per week, that overtime is voluntary and that it should not be more than 12 hours per week. Texport Overseas, which supplies Gap and Matalan denied that workers were forced to do overtime.

Employees of Texport Overseas factories claimed they were often made to meet unattainable production targets by working extra hours without pay. It is alleged the mostly-female workforce was bullied by male production managers for not achieving targets and were refused time off when ill. Texport Overseas denied the claims.

A spokesman for Primark said that the retailer took the allegations “very seriously” and that it had begun audits of all supplier premises and would ensure compliance if necessary.

Mothercare said it also took the allegations seriously and would re-audit its two factories in India.

H&M said harrassment and forced overtime is “unacceptable” and it would forward complaints to its suppliers. It said it required suppliers to ensure a minimum wage.

Ina statement, Gap said it regularly monitored suppliers and had recently experienced a “number of compliance violations at factories in the Indian sub-continent region” and would work to resolve the issues.

A spokesman for M&S said the two Gokaldas factories it used paid the legal minimum wage in India as “there is no legal or industry-agreed “ definition of a living wage. It said it was working to “better understand this complex area”.

Matalan said its suppliers paid above the minimum wage for Bangalore and that two compliance audits carried out on Texport Overseas in the past two years had revealed no record of forced overtime.