Retailers must do more to stamp out human rights abuses by their suppliers after a Guardian investigation found prawns sold in the UK were produced with the help of slaves, ministers are warning...Jenny Willott, the consumer affairs minister, said retailers must have a policy on sourcing ethical products, as ignoring the consumers' concerns about forced labour and dangerous working conditions could risk putting them out of business. In the first ministerial intervention since the exposé two weeks ago, Willott ordered the British Retail Consortium (BRC) to produce new guidance on urgent steps its members must take to improve transparency about human rights abuses linked to food, drink, clothing and other products. Karen Bradley, Home Office minister for modern slavery, also called on firms to stop working with suppliers with links to forced labour, saying they have a "social responsibility to ensure that those that they do business with are not involved in the exploitation of others"...Foreign Office minister Lady Warsi said the coalition will look to raise concerns with Thailand about the use of slaves to produce prawns sold in UK stores...Willott singled out high street giant Marks & Spencer for its long-standing and high profile "Plan A" ethical policy and the fashion retailer H&M for its clarity on ethical sourcing and information about its clothing ranges...[Refers to Carrefour, Costco, Tesco and Walmart].