British consumers are being forced to shop at supermarkets against their will, a survey suggests. A poll of grocery shoppers conducted by the Oxfam charity shows that just 11 per cent prefer shopping at supermarkets – despite the fact that 92 per cent do so. More popular are buying direct from farmers, local independent retailers or growing own food. The survey comes amid a growing debate about whether supermarkets restrict or provide greater choice in the range of products they sell. Consumers seem convinced that supermarkets hold the greatest power to influence Britain's grocery-buying habits. Forty-eight per cent said supermarkets could do the most to change shopping habits, compared to 30 per cent for consumers and 16 per cent for the government's potential impacts. Oxfam used the poll to draw attention to widespread concerns about ethical and environmental issues. The charity's director of trading, David McCullough, congratulated the Co-Op and Waitrose for their efforts in providing fair trade products and said competitors like Tesco and Asda should "take their lead from such groundbreaking moves". "By doing more to commit to fair trade practices and reduce their environmental impact, the biggest retailers can start to reverse the suspicion felt by many consumers over their huge influence," he suggested. Following a referral by the Office of Fair Trading last May, the Competition Commission is currently conducting a probe into whether supermarkets keep prices too high by restricting sector access to new competitors. Tesco, Asda, Sainsbury and Morrisons together control three-quarters of Britain's grocery market.