Darren Richards, from the Christian group Reflex, was speaking after council leaders warned that the number of children in custody risks increasing if plans to reduce in-year funding for Youth Offending Teams by an additional £9 million go ahead.
He told Premier the burden will fall to faith groups and the voluntary sector: "The Churches will always step up won't they?"
"Prison numbers are going to go up again and that will be really sad."
The Local Government Association is warning that the unexpected reduction to budgets will jeopardise local plans for youth offending teams.
Darren Richards also told Premier that the decision is unwelcome: "It's really sad and worrying - obviously we understand things are tight all over, and the government have these austerity measures in place - but actually what goes on in our prisons and in our communities in terms of offenders will ultimately ripple out and affect our communities."
He added that: "The less money there is to go around the harder it is for everyone both in the statutory sector, justice sector and also in the volunteer sector... to do what we're doing really."
Listen to Premier's Hannah Tooley speak to Darren Richards here:
