Some 80 prison officers did not attend their shift at Wandsworth Prison on the day that terror suspect Daniel Khalife escaped.
Prisons Minister Damian Hinds confirmed the level of staffing at the prison on Wednesday September 6 in response to a written question from Labour MP Dr Rosena Allin-Khan.
Khalife was apprehended in Chiswick, north-west London, last week by police after a four-day manhunt.
Mr Hinds said 125 Band 3 prison officers attended their shift on the day - equating to 61% of all staff expected to work. A Ministry of Justice spokesperson has told ITV News all of the staff absences on that day were pre-planned.
Overall staffing levels were above the minimum level required by the prison's Regime Management Plan to "deliver a safe and decent regime", the MP for East Hampshire added.
He said: "All staff in both the kitchen and the gatehouse were on duty on 06 September.
"An initial investigation into Daniel Khalife's escape did not find the staffing level to be a contributing factor."
Writing on X, the platform formerly known as Twitter, Dr Allin-Khan said she has had "concerns for many months about staffing levels" at HMP Wandsworth.
She said: "Today, it's revealed that on the day Daniel Khalife escaped - they were 80 prison officers short. This sits with the government. Their under-resourcing of the prison service has caused this."
The Ministry of Justice (MoJ) on Friday confirmed that a former director-general of the National Crime Agency has been appointed as the investigator into Khalife's escape.
Keith Bristow QPM served as the first head of the agency from 2013 to 2016, after spending five years as chief constable of Warwickshire Police.
Khalife, 21, was remanded in custody at Westminster Magistrates' Court on Monday after allegedly escaping from HMP Wandsworth by strapping himself to the underside of a food delivery lorry.
The MoJ said an independent investigation will seek to identify shortcomings and ensure lessons are learned to help prevent similar incidents.
A range of factors will be considered, including whether relevant protocols were in place at HMP Wandsworth when the escape happened and how Khalife was given access to materials that might have facilitated it.
Staffing levels and an assessment of relevant security measures, such as checks relating to the lorry, will also be scrutinised before findings and recommendations are provided.
The report on the investigation will be submitted to the Lord Chancellor and permanent secretary at the MoJ.
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