Banana Republic has begun an investigation in to allegations that Indian workers that make its clothes are being forced to work in situations that breach ethical best practice codes.

Ahead of today’s opening of Banana Republic’s flagship European store on Regent Street in London, the US retailer said it was “deeply concerned” by claims that the workers are being forced to labour for more than 70 hours a week for as little as 15p an hour.

Banana Republic, which is owned by Gap, said it made frequent visits to the factories in India to check that suppliers complied with the law and the company’s ethical code.

Gap’s senior vice-president of social responsibility Dan Henkle told The Guardian: “We have launched an immediate investigation into the allegations… we are looking at the factories in that area where production on our clothing is done, factories which also do work for a number of other retailers and plan to take appropriate action.”

The alleged plight of the Indian workers will be publicised by charity War on Want, which plans a demonstration at the opening of the London Banana Republic store.

Banana Republic flagship to open on Regent Street