In a speech today in York, the Labour leader said he wanted to know why Usman Khan was freed halfway through a 16-year jail sentence for plotting a terror offence in 2012.
Khan, who was set free in 2018, was one of 74 people jailed for terror offences who the Ministry of Justice confirmed were released early and did not serve their full sentence.
Mr Corbyn said: “I've asked for an inquiry into everything surrounding him, his sentence and what happened to him in prison, and what supervision order he was on afterwards.
“I want to know what kind of psychological assessments were made before he was allowed for release why the parole board was apparently not involved in the decision for his release. And also what role the probation service -- underfunded and broken up as it is because of privatisation -- was able to perform in monitoring his behaviour and his movements after coming out of prison.
“The priority has to be to keep people in the community safe. That is the point of a criminal justice system. That's the point of prison. That's the point of rehabilitation. That's the point of the probation service.”
Speaking on the Andrew Marr Show this morning, Prime Minister Boris Johnson said the attack at London Bridge was “nothing to do with parole, nothing to do with the probation service” and was caused by Usman’s early release last December.
“Legally there was no way of stopping him coming out early on the basis he was sentenced,” the Conservative leader added.
However, Corbyn said Tory cuts had deeply affected services, adding: “You can’t keep people safe on the cheap.”
Speaking to supporters at York College, Corbyn criticised previous governments, saying their actions have “fuelled, not reduced” the threat.
"Real security demands more than the correct operational decisions by trained and properly funded professionals, it requires political leadership as well.
"For far too long, our country’s leaders have made the wrong calls on our security.”
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Describing the attacks as “horrific in every way” Mr Corbyn warned however that Britain must avoid bringing in legislation that could increase terror instead of preventing it.
“I think we have to be careful that in the event of an atrocity, we don't bring in knee-jerk legislation, because that can itself pay a price, much later on.”
He referenced the 1974 Prevention of Terrorism Act, which “didn't help us bring about peace in Ireland, it probably made the situation worse because of the draconian nature of it”.
This echoed the words of David Merritt whose son was killed in the attack, and who said on Saturday night that Jack would "not wish his death to be used as the pretext for more draconian sentences or for detaining people unnecessarily".
In his speech, Mr Corbyn also praised the “extraordinary bravery” of the members of the public who intervened in the attack and said Britain owed “the deepest debt of gratitude” to the emergency services.
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York Outer, a seat held by the Conservatives, is reportedly a target seat for Labour, which doubled its vote share between 2010 and the last election in 2017.
Mr Corbyn said he was glad to be in the region, adding: “I’m always happy to be in Yorkshire. I love Yorkshire, it’s absolutely fine.”
He reiterated his commitment to a national investment bank which would “properly fund transportation in Yorkshire” and bring “high-paid skilled jobs”.
There was some confusion at the end of the speech, when Labour activists piled on double-decker buses, told Mr Corbyn would be giving a speech at a rally in the city centre.
However, by the time the buses pulled in to York Station and Labour members were herded to the rally, Mr Corbyn was already on his way to Whitby, where he was later pictured eating chips on the West Pier.