Sir David Ramsbotham said those seeking entry into the UK should be held in special immigration detention centres if it was deemed necessary to detain them while a decision was made.

There are currently 938 immigrants in detention - and just over half of them are kept in prison establishments rather than special centres.

Sir David: "Serious concerns"

In an inspection report on Haslar Holding Centre in Hampshire, he expressed "serious concerns" about locking up detainees in prison conditions.

Although Haslar is a holding centre rather than a prison, it is run by the Prison Service under prison rules.

Sir David praised the centre's staff for their humanity and care, but said it was "unacceptable" that rules intended for convicted criminals were being extended to detainees.

Prolonged periods of detention were "very stressful and can have an adverse effect on the mental health of a detainee", he said.

Sir David Ramsbotham: Wants to see "a swap of responsibility"

He told BBC Radio 4's Today programme that there should be a "swap of responsibility rather than an increase of places required", as promised by the government.

"I don't really see it's appropriate for people who haven't been tried by the courts to be held in conditions like that when actually it's the immigration service who should be holding them," he said.

He said the prison service should not have to run places like Haslar and pointed out that jails like Rochester Prison had had to set aside a whole wing for asylum seekers.

He also urged the government to process the forthcoming white paper on the issue as quickly as possible which would speed up the applications procedure.

Ugly reminder of home

Penal reformers supported Sir David's comments. The National Association for the Care and Resettlement of Offenders (NACRO) said being locked in a prison could remind asylum seekers of past imprisonment and ill-treatment in their own countries.

NACRO's Paul Cavadino: "Prison conditions can worsen the trauma of those fleeing torture"

Its spokesman, Paul Cavadino, said: "If people are fleeing from persecution, and in many cases from torture, then it can't be right for us to place them in the kind of prison-like conditions which are a constant reminder of the ill-treatment they suffered in their own country.

"Doctors who work for the Medical Foundation for the Prevention of Torture _ who have examined the people we're talking about have made it very clear that those conditions can worsen the fear, the trauma, the panic and the general psychological suffering that they are already undergoing."

More places in special centres

In its recent proposals to reform the immigration system, the government said detainees should be held in immigration centres rather than prisons and was planning to increase the number of spaces available in such centres.

But it predicted that prisons would still have to be used for reasons of "geography, security and control".

About 1.5% of applicants who could be liable to detention are held at any one time. They include people awaiting deportation, those who have entered the country illegally, and those considered at risk of slipping out of the immigration system.

The Home Office Minister Lord Williams of Mostyn said it was essential to detain some immigrants.

"Given the abuse we encounter and the involvement of organised crime," he said, "detention is a necessary part of our immigration control system. However we are committed to processing claims faster and pursuing adequate alternatives to detention."

Reformers say prison is the wrong place for immigrants

"Asylum seekers should only be detained in the most exceptional of circumstances, and never in prison," he said.

Under the 1951 UN Convention on Refugees, the Home Office is obliged to consider all the applications for asylum. Last year, the UK received 41,500 such applications, the second highest number in Europe after Germany.

That number is expected to have increased to 45,000 for 1998.