By Margaret Ryan BBC News Online

Conditions at Lincoln Prison are under the spotlight after rioting at the jail.

Prison service chief Martin Narey has admitted the high-security jail is overcrowded but has said it not a "hell-hole".

When rioting broke out on Wednesday there were 571 inmates in a prison which is designed to hold 370.

Prison officers say they warned only a fortnight ago about overcrowding at Lincoln.

Rapidly rising prison numbers, staffing problems and lack of resources are driving the Prison Service to breaking point

Juliet Lyon director of the Prison Reform Trust

And the prison's Board of Visitors had already expressed concern that a refurbishment project at the Victorian jail had to be postponed for two years because of overcrowding.

But Mr Narey, the prison service's director general, has denied poor prison conditions triggered the latest riot which saw 27 prisoners and three prison officers injured.

"There is not enough for prisoners to do, but it is a perfectly reasonable place."

On a visit to the prison two weeks ago he found it "well managed".

Refurbishment needed

An investigation will take place into this disturbance, which at one point saw inmates take over most of the prison.

But prison officers say they warned local prison authorities on 11 October that a situation was developing due to overcrowding.

Last month conditions were also criticised in a report on prisons in England and Wales by the Prison Reform Trust.

The Board of Visitors said overcrowding was affecting prisoners and staff, with one wing in desperate need of refurbishment.

The riots may further delay refurbishment

On a visit to the jail in May, the Board found prisoners were locked in cells for too long.

While some refurbishment had taken place, work on another wing has had to be postponed.

A Home Office spokesman would only say a complete refurbishment of four wings had begun three years ago.

Wednesday's eight hours of rioting can only have put back this refurbishment further after inmates set fire to parts of the jail.

Lincoln Prison, which opened in 1872, is a category B local prison and is designed to accommodate about 370 inmates.

But its operational capacity - the number of prisoners it can hold safely - is 552, according to the Prison Service.

It takes remand and convicted prisoners but is beginning to take a greater proportion of the latter.

Among its high profile inmates has been Lord Archer, transferred to the closed prison in September after he breached open prison rules.

Warnings issued

A prison service inspection report in December said the jail had some way to go to "provide appropriate regimes and services for its varied population".

Overall it praised work done to improve conditions and found 80% of prisoners felt safe.

Lincoln Prison

Opened 1872 Category B local prison Operational capacity 552 571 inmates during riot Refurbishment began 1999 Governor Richard Peacock

But Juliet Lyon, director of the Prison Reform Trust, said the latest riots again raised the wider issue of prison overcrowding.

"Rapidly rising prison numbers, staffing problems and lack of resources are driving the Prison Service to breaking point".

"It is a tragedy that a riot causing severe damage and serious harm should break out when both the risks and the solutions have been spelt out for so long," she said.

She called on the government to press ahead with plans to reserve prisons for the most violent and serious offenders.

More than 72,000 people are now in jail - numbers that prompted the Prison Governors' Association to warn earlier this month that places would run out by January.

Following Wednesday's riot Brian Caton, the association's general secretary, again warned many overcrowded prisons were reaching "crisis point".