Inmates at Lincoln Prison were handed nearly 300 extra punishments in just three months after breaking rules, figures show.
Drastically curtailed prison regimes, cell confinements and other restrictions contributed to a national drop in adjudications – hearings which take place when a prisoner is accused of rule-breaking – during the coronavirus pandemic, experts say.
Ministry of Justice data shows 384 adjudications were recorded concerning possible rule breaches at Lincoln Prison between January and March, down from 419 during the same period in 2020.
Of those, 263 (68%) resulted in a guilty verdict.
Adjudicators can punish inmates with a range of disciplinary measures, from adding days to their sentences to stopping earnings and taking away their privileges.
Separate figures detailing punishments handed to prisoners during that period show inmates were ordered to spend a total of 185 extra days – around 26 weeks – in jail after committing offences while behind bars.
Punishments recorded in that quarter included 28 cases involving violence, 166 linked to disobedience and 37 concerning unauthorised transactions, which could involve drugs or alcohol.
Unruly convicts at Lincoln Prison, some of whom may have received more than one punishment at an adjudication, were handed a total of 292 punishments between January and March, with the most common being the forfeiture of privileges.
More than 37,200 adjudication outcomes were recorded across England in that time, a fall of more than a quarter compared to the same period last year.
Additional days were given as punishment on 747 occasions, with nearly 12,000 days added to sentences in that quarter, 84% fewer than in 2020.
Frances Crook, chief executive of the Howard League for Penal Reform, said additional days could pile pressure on the prison population and worsen overcrowding, rather than solve problems.
She added: "The prison system has been hugely impacted by the coronavirus pandemic, with institutions running drastically curtailed regimes that keep prisoners isolated in their cells for the vast majority of the day.
"These draconian restrictions have impacted on adjudications and the imposition of additional days of imprisonment."