Eight asylum seekers have gone missing from a former army barracks which is being used to house migrants, the Home Office confirmed.
Those staying at Napier Barracks in Folkestone, Kent, are free to live elsewhere but must supply an address.
Failure to do so may result in their asylum claim being withdrawn, the Home Office said.
Damian Collins, the Conservative MP for Folkestone and Hythe, said he was "extremely concerned".
The eight people went missing between 22 September, when the site opened, and 20 October, the Home Office has confirmed.
The Home Office is obliged to provide accommodation and support for asylum seekers while their claims are considered.
About 400 men are staying at the Napier Barracks with those at the centre sleeping in socially-distanced dormitories.
'Questions about security'
Mr Collins said: "I'm extremely concerned that since September eight asylum seekers have disappeared from the barracks, their current location unknown and their applications presumably suspended.
"The number of asylum seekers that have already left the camp raises serious questions about the security of the Napier Barracks facility."
Mr Collins said he had written to the Home Office to demand urgent clarification of what had gone wrong.
The Home Office spokesman said nobody staying at these sites was being detained and they were free to make alternative arrangements. but must give their new addresses.
"If a person absconds before a decision is made, or if they fail to comply with our processes, their asylum claim can be withdrawn," he said
He added details of those missing from the centre had been passed to police.