It comes after the Prime Minister ordered an urgent review of prison sentencing.
In a bid to crack down on crime, Boris Johnson wants to end automatic early releases - where dangerous offenders are let out of prison mid-sentence.
Under current legislation, offenders sentenced to 12 months or more serve the first half of their time in prison and the second "on licence" in the community, where they can be recalled.
Over the weekend Mr Johnson pledged up to £2.5 bn to create 10,000 extra prison places and expand stop-and-search powers.
The Prison Advice & Care Trust (PACT) is a Catholic charity that has worked within the justice system for 120 years.
PACT CEO Andy Keen-Downs told Premier's News Hour that increasing sentences will not reduce crime rates.
He said: "Sentences have actually been getting longer, significantly longer the last 10-20 years.
"What all the experts point to is that longer sentences are not actually a deterrent to people from offending - they don't stop people offending."
Mr Keen Downs says the PM's solution is a band aid for a bullet wound: "If young people are carrying knives, because they're frightened, because other young people are carrying knives, they're not going to not carry a knife, because they think the sentence is going to be longer.
"They won't carry a knife if they feel safe in their own communities."
Mr Keen Downs says big prisons are not the solution and the money could be better spent elsewhere to support the prison system.
"There are not enough prison officers, there's not enough education, there's not enough housing for people when they come out of prison, and we've got so many challenges with the system.
"The idea of spending two and a half billion on huge prisons in remote areas, that are away from people's families, away from faith communities and jobs seems to me to be a plan of desperation or electioneering."
He says the Church has a role to play in supporting prisoners in their rehabilitation.
"Catholic Bishops have said very clearly, the wall of a prison is no barrier between you and your parish, you're still part of our community, whether you're in prison or at home.
"That means the role of prison chaplains is very important and volunteers and initiatives helping offenders get a fresh start.
"If you're in the middle of absolutely nowhere, and your newest parish is 50 miles away, it's really difficult to maintain that relationship of faith and relationship.
"I've met so many people who rediscover their faith or come to faith in prison, and it's what sustains them through that very dark time."
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