A Norfolk prison where the inmate population has gone up by 300 in three years has increased the use of force, a government report has said.
HMP Wayland Prison in Thetford houses 1009 category C male prisoners and was subject to a surprise Ministry of Justice inspection in April.
The report said overall the prison was performing "reasonably well".
But added there had been an increase in the use of force and "healthcare was not sufficiently resourced".
The prison was last inspected in 2006 and in June 2008 it underwent a major development to build five new house blocks.
Education, healthcare and segregation units were also revamped.
Dame Anne Owers, Chief Inspector of Prisons, said: "Wayland had nearly doubled its population since our last inspection and this had placed considerable pressure on the prison.
"Some areas, particularly reception and healthcare, were now struggling to cope with the numbers of prisoners that needed to be dealt with, while relationships between staff and prisoners appeared to have deteriorated.
"Nevertheless, while worrying, these visible strains should not obscure much other good work that had been sustained."
Parole review delays
The report added: "Managers and staff deserve credit for managing the expansion in a way that ensured that Wayland remained a largely safe and purposeful prison, with a sound focus on resettlement."
The report also said prisoners had "good time out of cell" but that there were too few activity places for the number of prisoners.
Education, work and training were praised and resettlement was described as well-managed.
But the report stated the increasing numbers of prisoners on indeterminate-sentences meant they were left frustrated by the limited provision and the delay in parole reviews.