The government should stop pursuing carers with huge fines until it investigates whether it is to blame for overpaying them, according to a former Conservative work and pensions secretary. Iain Duncan Smith called on the department to stop hounding people for the repayments and investigate its own responsibility for the errors, some of which have left unpaid carers with criminal records and deep in debt. Duncan Smith told the Guardian: “We don’t want people being forced into very serious difficulty. My advice is to pause this and review very carefully what’s been going on.” The Guardian has revealed that carers are being forced to pay huge sums to the government and threatened with criminal prosecution after unwittingly breaching earnings rules by just a few pounds a week. People who claim the £81.90-a-week carer’s allowance for looking after loved ones are being pursued by the Department for Work and Pensions (DWP) to pay back money that has been wrongly overpaid to them, in some cases running to more than £20,000, or risk going to prison. Duncan Smith’s intervention piles pressure on ministers to act. “The best thing is for the DWP now to pause any of these demands, review carefully what was behind all of this to make sure this was not mistakes by DWP but is genuinely about individuals failing to notify the department,” said the former Tory leader. He called for carer’s allowance to be subsumed into universal credit and said the government needed to learn the lesson from tax credits, where benefits claimants have been pursued to return money they were paid because of DWP errors. The Carers Trust, which represents more than a million unpaid carers across Britain, accused the government of “hounding” and “ruthlessly pursuing” carers who were being pushed into poverty as a result. The repayments have mainly hit carers on low incomes. They have been criticised as a draconian response to mostly minor earnings rules infringements caused by DWP oversights. Dominic Carter, the Carers Trust director of policy, said: “The vast majority of these overpayments have been genuine mistakes as a result of an overcomplicated and broken carer’s allowance system. “The Department of Work and Pensions needs to write off these fines, stop hounding this country’s devoted unpaid carers and focus instead on fixing that system.” Lloyds Bank Foundation, the charitable body founded by Lloyds Bank, also joined the calls to overhaul the system. Paul Streets, its chief executive, said there needed to be “wholescale reform” of a system that was unfairly punishing unpaid carers for unknowingly exceeding the earnings limit. He added: “We need an urgent reform of carer’s allowance so that those caring for loved ones who are disabled or ill get adequate support.” The Liberal Democrats, several Tory MPs and the Centre for Social Justice, a centre-right thinktank, have urged the government to stop pursuing carers and accept it was to blame for the overpayments. The former justice secretary Robert Buckland said the DWP “shouldn’t be treating these carers as criminals” and that “it’s utterly repugnant and wrong”. Ministers are refusing to publish the findings of an official study into the emotional and financial impact of the fines. About 6 million people in the UK are unpaid carers, devoting much of their lives – and often giving up full-time work – to look after partners and relatives who are disabled, frail or ill. About 1 million people who provide unpaid care for more than 35 hours a week claim £81.90 carer’s allowance, a non-means-tested benefit.