London — Fashion group H&M was failing to keep a "living wage" promise, forcing many employees in its factories to work excessive hours to survive, civil society groups said on Monday.

Based on interviews with 62 people in six H&M supplier factories in Bulgaria, Turkey, India and Cambodia, campaigners said none of the workers earned anything near a wage that could cover basic needs.

Big brands are under mounting pressure from campaigners and consumers to improve working conditions in global supply chains, and render them free of exploitation and slavery.

The Clean Clothes Campaign (CCC) said Sweden’s H&M, the world’s second-largest fashion retailer after Zara owner Inditex, had not met a 2013 commitment to ensure its suppliers paid a living wage to 850,000 textile workers by 2018.

"H&M needs to take action immediately to stop the scandal of poverty wages and workers’ rights violations," said Bettina Musiolek of the CCC, an alliance of labour unions and charities.

H&M, with more than 4,800 stores in 69 countries, said it had reached at least 600 factories and 930,000 garment workers with its fair living wage strategy.

"There is no universally agreed level for living wages, and wage levels should be defined and set by parties on the labour market through fair negotiations between employers and workers’ representatives, not by western brands," said an H&M spokesperson.

The CCC said workers in H&M supplier factories in Cambodia earned less than half the estimated living wage, dropping to about a third for those in India and Turkey. Many worked overtime longer than the legal limit without being properly paid.

Others got only the minimum wage if they worked extra hours and met quotas, which the UN said was forced labour, the CCC said.