The wooden huts of Low Moss Prison outside Bishopbriggs, a low-security jail which holds a fifth of Scotland's adult male convicted prisoners, were yesterday described as resembling a prisoner of war camp by Mr Clive Fairweather, the chief inspector of prisons in Scotland, who said it could not be long before the huts began to fall down.

His report recommends that an early decision is made on the future of the jail, which was a war-time RAF camp.

He also pointed out that the current lease from the Ministry of Defence is due to expire in 2002.

He acknowledged that Low Moss was playing a vital role for the Scottish Prison Service but added that it had originally been intended ''that these wooden relics from the beginning of the Second World War would be used as a temporary means of relieving overcrowding in Barlinnie'' when it opened as a jail in 1969.

Mr Fairweather said that unless decisions were taken soon on rebuilding the prison, large numbers of men would continue to be housed in inappropriate conditions for another decade or more.

''Is this what we would expect from a modern prison service? I am not mincing my words when I say that Low Moss looks to me like a prisoner of war camp. All that is missing is a wooden horse in the square with prisoners trickling sand down their trouser legs. At Low Moss they would not need to tunnel out but most of the prisoners are not interested in escaping,'' he said.

For obvious reasons, he said, the prison did not take anyone convicted of fire-raising or those who had a history of attempted escapes.

''We will need Low Moss in the future but we can't just go on with wooden huts. There are other reasons for replacing these buildings - the passages, for example, are ideal locations for assault and, although we could not prove it, we are certain there are high levels of bullying in the dormitory situation,'' he said.

One positive result of communal living was that there had been no suicides at Low Moss. The inspectorate also praised the remedial work being undertaken with addicts with a total abstinence approach, but it was critical that the numbers who had been through the 12-week course were low. The inspectorate expressed disappointment at the lack of a comprehensive anti-drugs strategy for the majority of the prisoners.

However, Mr Fairweather observed that the prison had acted quickly to appoint a full-time drug worker, a key appointment which would benefit all the community as well as the prison.

In a statement, Mr Henry McLeish, the Home Affairs Minister, acknowledged the need to replace the huts ''in due course'', adding that that would not be achievable in the foreseeable future as the priority was to relieve the general overcrowding in the system. The jail's long-term future and its condition was being addressed by an SPS estates strategy review.

Local councillor Billy Hendry said yesterday: ''The fact that the inspectors have made such a critical attack on Low Moss reinforces what we have been saying for years - the place is totally inadequate. With Mr McLeish's reluctance to take any action there is now a clear case for winding down Low Moss and closing it once and for all.''