UK grocery retailer Co-op has announced that it is switching all its own instant and ground coffee to Fairtrade.

The Co-op, which is currently the UK's leading retailer of Fairtrade products, is also calling on big multinational roasters, such as Nestlé and Kraft, to launch their own Fairtrade coffee brands.

The Co-op said its conversion to 100% Fairtrade will boost the value of the UK Fairtrade coffee market by 15% or £4m (US$6.7m).

Under the Fairtrade initiative, coffee growers receive a fair price, currently double or triple the global market price.

The Co-op said its decision follows Oxfam's revelation that, with global coffee prices at their lowest in real terms for 100 years, 25 million small growers are facing starvation because their labour no longer provides a living.

Last year the Co-op switched its entire own-brand chocolate bar range to Fairtrade.