A total of 91 prisoners were freed by mistake between April and October this year, according to new government figures.
The data for England and Wales was published by the Ministry of Justice, as ministers face pressure over accidental releases after a number of high-profile cases in recent weeks.
Justice Secretary David Lammy told MPs the figures were “symptomatic of a prison system under a horrendous strain”, saying the Labour government had inherited a “crisis” from the Conservatives.
But shadow justice secretary Robert Jenrick said “the confusion created by Labour’s botched early release scheme”, which was brought in to ease prison overcrowding, was partly to blame.
The number of accidental releases has been increasing in recent years.
A total of 262 prisoners in England and Wales were freed by mistake in the 12 months to March, according to the latest annual figures, up 128% from 115 the previous year.
The latest data released by the Ministry of Justice covers a seven-month period between 1 April and 31 October.
The department said the figures cover any prisoner who is released when they should have remained in custody, where the individual or a third party did not deliberately play a role in the error.
It said the data was not directly comparable to annual figures, with the possibility of seasonal effects on releases and late recordings.
The department added that figures for recent months could change over time and in the past revisions “have tended to be upwards”.
