Just 17% of workers say their companies are serving fair trade products at work, while 38% say they believe their employer should make them available, according to research from the Fairtrade Foundation.

The survey of 2,300 people by YouGov was published to coincide with the Foundation's latest campaign - Fairtrade at Work - which is backed by a website, www.fairtradeatwork.org.uk, explaining how companies can switch.

M&S, which only sells fair trade coffee and tea in its stores, supported the campaign by distributing leaflets about the campaign to staff and putting up posters around drinks machines. Other retailers to make fair trade products available to staff include The Co-operative Group, Asda and Waitrose.

Harriet Lamb, executive director of the Fairtrade Foundation, said: "This campaign aims to see the availability of Fairtrade products in the workplace match that in the shops."