The government has run out of prison places and has had to ask police to use 400 cells to make up for the shortfall.
Prisons Minister Damian Hinds told MPs there had been an “acute and sudden increase in the prison population” in recent months and, as a result, the Operation Safeguard contingency plan had been launched for the first time since 2007.
He claimed the move was not “unprecedented” and that the government had “long anticipated” the rise due to bringing in additional measures to tackle crime.
But Mr Hinds also pointed to strike action by the Criminal Bar Association, saying it had led to more people being held on remand.
And he said with court hearings returning to normal, the government was “seeing a surge in offenders coming through the criminal justice system, placing capacity pressure on adult male prisons in particular”.