The National Audit Office (NAO) said the scheme had not delivered value for money, it had caused hardship for many people and its roll out was happening more slowly than intended.
Adding his criticism, policy adviser at The Methodist Church, Paul Morrison said: "What we've been watching is a slow car crash of a benefit roll out.
"The problem is that the people who are trapped in that car crash - the people who are being damaged - are not being listened to and are, at times, being straightforwardly ignored."
A spokesman at the Department for Work and Pensions (DWP) insisted that UC is "good value for money", adding that evidence shows claimants are "getting into work faster and staying in work longer".
Emma Revie from the Trussell Trust charity - which supports hundreds of church-run foodbanks - told Premier 70 per cent of people they spoke to fell into debt making the switch to UC.
She added: "In our experience, it's taking too long to sort and - whilst it's being sorted out - hundreds of thousands of being are being affected adversely.
"Many of them are ending up at our foodbanks requiring emergency food..."
The NAO said UC - which is replacing six payments including job seeker's allowance, tax credit and housing benefit - cost more to administer than the previous benefits.
The DWP spokesman said: "Previous administrations poured billions into an outdated system with a complex myriad of benefits, which locked some people into cycles of welfare dependency, whereas we are building a benefit system fit for the 21st century, providing flexible, person-centred support, with evidence showing Universal Credit claimants getting into work faster and staying in work longer."
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