Valentine’s Day is the most lucrative date in the flower retailers’ calendar yet workers in developing countries are risking their health and toiling for a pittance supplying British supermarkets.

Bouquets are sold for vastly inflated prices but research by anti-poverty charity War on Want has found the mainly female workforce in Colombia and Kenya supplying those flowers continues to slave for as little as half the living wage.

Workers also suffer problems such as disabling repetitive strain injuries and miscarriages through exposure toxic to pesticides, the charity said.

Supermarkets sell around 70 per cent of all the flowers bought in Britain — the highest proportion in Europe.

While many British firms have adopted voluntary standards for their suppliers, these are still failing to protect the health and safety of workers or ensure basic workers’ rights.

War on Want believes government regulation is necessary to introduce binding legislation to hold companies to account for the impacts in their supply chains.

It argues that workers supplying multinational companies in Britain should have the right to redress in this country and the ability to seek compensation for damage to their health or loss of earnings as the result of actions of British companies and their suppliers.

The charity is calling for the establishment of a supermarket watchdog to tackle abuses by British firms and their suppliers.

War on Want spokesman Paul Collins said: “Millions of people buying Valentine’s Day roses for their loved ones will be shocked to learn that many workers supplying them face poor pay and conditions.

“It is nothing less than a disgrace that company bosses are piling up profits while Kenyans on flower farms struggle to feed themselves and their families, and live in slum housing. British corporate leaders must ensure a living wage and decent conditions for them.”

Mr Collins added that with London Fashion week due to begin today, “we urge shoppers not only to press retailers on flower workers’ treatment, but on the need to guarantee a living wage and good, safe conditions for those who make our clothes or supply fruit, tea and wine sold in UK stores.”