The Home Office has made “unacceptable and avoidable mistakes” in its haste to use disused airfields and a barge to house asylum seekers, parliament’s spending watchdog has concluded. The public accounts committee said the department “does not have a credible plan” to send asylum seekers to Rwanda and has little to show for hundreds of millions of pounds spent so far on the policy or its accommodation plans. In a report released on Wednesday, MPs said the Home Office claimed that its need to deal with a “national emergency” meant it had to take quick decisions, and so “it pressed ahead with setting up expensive large asylum accommodation sites without an adequate understanding of what would be required”. The Home Office spent £230m on establishing four large accommodation sites – the Bibby Stockholm vessel in Dorset, former RAF bases in Wethersfield, Essex, and Scampton, Lincolnshire, and former student accommodation in Huddersfield. The sites programme is expected to cost £1.2bn in total, the committee said. At the outset, the Home Office estimated that costs to convert the former RAF bases would be £5m for each site but they increased to £49m and £27m respectively. While the committee welcomed the department’s efforts in moving asylum seekers out of hotels, it found that the “assessment of the requirements for setting up alternative accommodation in large sites fell woefully short of reality and risked wasting taxpayers’ money”, and the new sites “will not house anywhere near as many people as initially expected, exacerbating existing accommodation issues”. On Tuesday it emerged that plans at Scampton, once home to the 617 Squadron that flew the Dambusters raids, had been scaled down. Originally, 2,000 asylum seekers were due to be housed there, but the Home Office now says “up to 800” will arrive in total. In the case of the contract for procuring the Bibby Stockholm, which now houses asylum seekers in Portland, Dorset, there was only one supplier on the framework used, which meant there was no opportunity for competition, the committee said. “The Home Office’s latest assessment of value for money from January 2024 suggests that, in total, large accommodation sites will cost £46m more than the hotels they are intended to replace,” the report said. In the report’s conclusions, the committee said the Home Office had “continually failed to be transparent” and singled out the permanent secretary, Matthew Rycroft, for not providing information. “We are left with little confidence in the Home Office’s ability to implement the Rwanda partnership and its understanding of the costs, particularly given its track record in delivering other major programmes,” the report said. Yvette Cooper, the shadow home secretary, said: “This damning report makes clear, as Labour has long said, that the Conservatives have no credible implementation plan. “Rishi Sunak knows his gimmick won’t work to stop boat crossings – that’s why he has called an election, to prevent the entire scheme from unravelling.” Responding to the report, the home secretary, James Cleverly, said: “The cost of housing asylum seekers will reach £11bn a year by 2026, which is why our Rwanda scheme is so important. “Labour have no plan to stop the boats – they would scrap our Rwanda scheme and grant an amnesty to hundreds of thousands of illegal migrants with no right to be here.”