Asylum seekers have been moved from a former RAF base after radiological contamination and unexploded ordnance were located.

70 people were transferred from the Home Office’s largest mass accommodation site to hotels after a number of safety concerns were raised.

The Wethersfield airfield site in Essex was set to be used to house asylum seekers for a three-year period after planning permission was granted last month.

But a special development order (SDO) found issues with a contamination risk from gases, radiological contamination and unexploded ordnance, as well as with suitable storage for fuel and other hazardous substances and satisfactory arrangements for drinking water.

The move is another blow to the Home Office’s plans to reduce asylum seeker hotel use.

A report from the National Audit Office suggested that huge accommodation sites were more expensive than hotels.

It follows similar safety concerns at RAF Scampton in Lincolnshire which was forced to scale back its numbers from 2,000 to 800 due to contamination and unexploded ordnance risks.

The Home Secretary has been told to launch "a programme of intrusive ground investigations to assess contamination" at Wethersfield.

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The site was set to open this month but it has reportedly been delayed until June.

Graham Butland, the leader of Braintree district council, said they wrote to the Home Office "requesting urgent copies of all the relevant technical documents and plans under the SDO to support our duty in safeguarding the interests of the local community and those living or working on site".

He added that the council was still waiting for a response from the Home Office.

"The Home Office continues to put the health and welfare of men at RAF Wethersfield at risk," Maddie Harris, the director of Humans for Rights Network, which supports asylum seekers told The Guardian.

"We have heard from hundreds of men held there, now further supported by the contents of the SDO, that the site is not fit for purpose.

"Rather than provide safe and secure accommodation, the Home Office insists on pursuing its harmful policy of accommodating men in poor conditions."

The Home Office said: "We have always been clear that the use of asylum hotels is unacceptable, which is why we moved asylum seekers to former military sites which we ensure are safe to accommodate asylum seekers prior to use."