Prisoners at Scotland’s biggest jail should be able to use their own bedding and should be able to access reliable hot showers, while new furniture should be provided for cells, according to Scotland's prisons watchdog.

Her Majesty's Chief Inspector of Prisons David Strang said mattresses in cells at Glasgow's Barlinnie Prison were too thin, and the pillows too hard.

He called for changes to help improve conditions he described as unfit for modern use, and demanded the Scottish Prison Service look at replacing the 134 year old Victorian jail.

Mr Strang said the Scottish Prison Service had been told for 16 years that Barlinnie needed to be replaced, but there was little sign of progress and the reception area where prisoners are held when they first arrive is inadequate.

He added: “These observations and requests for change appear to have been ignored by the SPS. Plans for HMP Barlinnie?s replacement or significant investment in the reception facilities are urgently required.”

He also said: “We are disappointed that the SPS has not brought forward plans for the replacement of HMP Barlinnie or delivered the necessary investment to address the issues identified previously, yet have invested significant sums in other parts of the establishment.”

The report says staff at the jail do a good job of treating prisoners decently and managing the limitations of the historic buildings.

But Mr Strang said despite "the obvious care and compassion" staff show, "they are

being asked to operate in conditions that are unacceptable in the 21st Century".

The report it calls for improvements to make life easier for inmates – he said Barlinnie had been marked down in the report because prisoners wer not allowed their own bedding and said managers should address the situation as a matter of urgency.

The report says prison bosses should also consider ordering different bedding. It adds: "The SPS should consider

reviewing their mattress specification as the ones currently provided are thin and when compressed it was possible to feel the bed structure below. The pillows provided were very hard and not of the standard that we had found in other prisons."

Furniture in cells is well-worn, it says, and also not as good as that in other jails. Inspectors could not get showers in one hall to run hot until the third attempt, and the report says they should be fixed.

The age and layout of the health centre and the prison in general are also criticised, with limited space to see patients and very few cells accessible for disabled prisoners. Cell doors are not wide enough to allow wheelchair access or big enough for specialist lifting equipment, but the age of prisoners are increasing.

The report also draws attention to the fact that Barlinnie has seen a near quadrupling of the number of sex offenders it holds. This too causes a problem as many are much older than the average prisoner.

Mr Strang also said staff should get more training in equalities after inspectors spoke to one prison officer who talked about "coloured" people and "the gays". They said he spoke "without any awareness of the offence that these terms cause."

Mr Strang said the prison was well-run with a strong sense of identity but the age of the accommodation provided considerable challenges.

He said changes including a new unit for long term prisoners and lifers nearing release, and a quadrupling in the number of sex offenders housed were placing new pressures on the prison."The impact of these significant changes should not be underestimated and management must ensure they have the resources required to adapt to the new challenges they face," he said.

A spokeswoman for the Scottish Prison Service said: "SPS is pleased to note that the report recognises efforts of staff at HMP Barlinnie to limit the impact of outdated facilities on prisoners. While replacement of HMP Barlinnie’s reception has been previously considered, the full replacement of HMP Barlinnie remains the preferred option at this time."