Britain's supermarket price wars are trapping tens of thousands of banana farmers and workers in an "unrelenting cycle of poverty".

According to the Fairtrade Foundation, in the past 10 years the UK supermarket sector has almost halved the shelf price of loose bananas while the cost of producing them has doubled.

UK consumers now typically pay 11p for a loose banana compared with 18p a decade ago, while a loose apple grown in the UK now costs 20p.

But living costs for banana farmers and workers in the three countries that provide 70% of the UK's bananas - Colombia, the Dominican Republic and Ecuador - have rocketed by 85%, 350% and 240% respectively.

"Small farmers and plantation workers are the collateral damage in supermarket price wars," said Michael Gidney, chief executive of the Fairtrade Foundation.

He added: "The poorest people are bearing the cost of our cheap bananas and they have to work harder and harder as what they earn is worth less and less in their communities."

The study argued that as bananas are the fourth most important food crop in the world and one of the most valuable agricultural commodities in global trade, it is wrong that they do not guarantee a sustainable living for all the people involved in producing and supplying the market.

The Fairtrade Foundation also claimed that the unrelenting downward pressure on banana prices has driven a shift in many banana producing countries towards job losses, the casualisation of labour and the marginalisation of smallholder producers.

The organisation called on the UK government to urgently step in and investigate the impact of retailer pricing practices.

A Department for Business, Innovation and Skills spokesperson said: "We fully recognise the positive impact that the Fairtrade brand can have on consumer's shopping habits and in raising awareness of supply chain issues.

"However, it is not our policy to get involved in price-setting. The price that people pay at the checkout is down to the supermarkets. If there was a case for a competition issue then the Office of Fair Trading would be able to consider investigating."

The British Retail Consortium, which represents UK supermarkets, had not responded to a request for comment at the time of publication.

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