Prison breaks have become more common under the coalition government, Labour claimed last night.
The accusation comes as authorities try to track down John Massey, a convicted murderer who escaped from Pentonville prison this week.
"Prison escapes are becoming a habit under this Tory-led government," commented shadow justice secretary Sadiq Khan.
"Yesterday's escape represents another serious lapse in security and it's important there should be a thorough and open investigation of what went wrong.
"The authorities must act quickly to recapture the escapee to remove any threat to public safety."
Massey, 64, is understood to have hidden in the prison gym and then scaled the roof with netting designed for sporting activities.
He was serving life for a pub murder in 1975, when he shot a bouncer with a sawn-off shotgun.
The security breach is a major embarrassment for the Ministry of Justice, which has launched an investigation into the case.
It is not entirely clear whether the Labour accusation stands up. The last escape from Pentonville was in 2009, when Gordon Brown was prime minister.
Julien Chautard spent just minutes in the prison before he escaped by clinging to the underside of the same security van he had arrived in.