More than 500 migrants will be housed at a military base which is "vital" to the British Army, Army Reserves and the cadets.

Home Office documents show up to 540 asylum seekers will live at Crowborough Training Camp in East Sussex.

Channel migrants will receive food and laundry services whilst staying at the site.

It will only hold single, adult, men and they will be able to "come and go" as they will not be detained at the site.

They will also be told how to behave in the local community to avoid anti-social behaviour.

Officials said: "Key services, including accommodation, catering, and laundry, are available on site, so while asylum seekers are free to come and go - as the site is non-detained - these essential needs are met without them having to leave."

But there are fears the decision to house migrants on military bases could hit training for British troops.

Lord Lancaster, the former Director of Reserves for the British Army, said: "The MoD training estate is oversubscribed; indeed, that is one of the biggest factors when it comes to trying to train the Army Reserve.

"While I commend to the Minister the announcement in the Strategic Defence Review that the reserve and cadets will be expanded, this will place even greater pressure on the MoD's training estate.

"Crowborough training area is a vital estate used not just by cadets but by the reserve and the regular Army. I simply ask the Minister to be very careful about the selection of sites that we choose. It is not just about the accommodation; it is the second-order impact on the estate."

Meanwhile documents show around 300 migrants will be held at Cameron Barracks in Inverness.

Both sites will only be used for up to 12 months, the Home Office claims.

The Home Office added: "Making use of existing basic accommodation on MOD sites such as Cameron Barracks is just the first step in the government's work to exit hotels and source more appropriate accommodation to meet our statutory obligations.

"We hope to have alternative, longer term accommodation options up and running within about 12 months, which will enable us to return Cameron Barracks to MOD use."

Explaining the overall policy, officials added: "The government is determined to restore order to the asylum system so that it operates swiftly, firmly, and fairly; and ensures the rules are properly enforced. We have committed to exiting hotels at the earliest opportunity, and in order to do this we need to stand up alternative accommodation which is better suited to this purpose."