The supermarket, which is the world’s largest retailer of Fairtrade products, has announced a pilot project called Fairly Traded.

It will see the supermarket offer farmers a guaranteed minimum price for their crop and deliver a “social premium” by reinvesting profits from Fairly Traded branded tea through the Sainsbury’s Foundation.

But the plan has been criticised because the Foundation’s advisory board of academics, charities and NGOs will devise the projects.

The Fairtrade Foundation has argued that the model will deprive farmers of control over their production.

Charity Oxfam has said it is “crucial that any new initiative matches the standards of the Fairtrade Foundation or builds on them”.

A spokesperson for Sainsbury’s has insisted that the supermarket is “matching all the benefits of the Fairtrade model and building on them”.