The group said the move would boost the UK fair trade coffee market by 15%, or about £4m, a year.

World coffee prices are now at a 30-year low with many farmers selling coffee for less than it costs them to produce it.

Sales of fair trade coffee increased by almost a third last year, according to the Fairtrade Foundation.

Growing popularity

Under fair trade, coffee growers get a better price, currently double or triple the global market price.

It's the simplest way we can make a real and immediate difference Malcolm Hepworth, Co-op

Adrian Lovett, Oxfam's Director of Campaigns, welcomed the move.

"The Co-op is setting a global standard for the coffee companies to follow," he said.

"Buying fair trade is the simplest way for shoppers to help coffee farmers and the Co-op is providing what consumers want - coffee with a conscience."

Malcolm Hepworth, chief operating officer at Co-operative Retail, said: "The coffee crisis is complex, and fair trade is only part of the solution.

"But it's the simplest way we can make a real and immediate difference. Immediate, because all consumers have to do is buy fair trade. Real, because growers will get much more for their coffee."

Boosting sales

The Co-op is sourcing its fair trade coffee, which will be used to make its instant and ground coffee brands, from five farmer co-operatives - four in Central and South America and one in Tanzania, East Africa.

It believes the switch should increase its existing sales of fair trade coffee from £2.1m to £6.5m, it said.

Co-op will continue to stock both conventional and other fair trade labels.