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Prison numbers cannot be cut with "dangerous quick fix" solutions, the justice secretary has said.

Liz Truss said the overcrowding is down to more criminals serving time for violence and sex crimes.

She called for early interventions and better reforms but not shorter sentences, after a BBC investigation revealed chaos at one jail.

The Howard League said the problems uncovered were seen in "almost every prison in the country".

The Ministry of Justice said it would investigate disclosures by the Panorama programme about HMP Northumberland, which included widespread drug use, a lack of control, door alarms that did not go off in one block and a hole in an internal security fence.

The BBC's home affairs correspondent Danny Shaw said Ms Truss' speech focused on tackling the "appalling" number of re-offenders but did not feature a major policy announcement or sweeping changes in direction. The key points of her speech were:

Having a beefed up prisons inspectorate "with teeth" so that the justice secretary can be held to account over its recommendations

Improving rehabilitation programmes

Getting more targeted help for drug offenders

No change on the rules around indeterminate sentences for public protection

The current rate of re-offending within a year of conviction is 25.3%.

Speaking to the Centre for Social Justice, Ms Truss said: "Reductions by cap or quota, or by sweeping sentencing cuts are not a magic bullet, they are a dangerous attempt at a quick fix."

The most recent figures put the population of inmates in England and Wales at 85,490 in 2016 - up from 50,962 on average in 1995.

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Media playback is unsupported on your device Media caption Undercover footage shows prisoners incapacitated by drugs

Ms Truss said more sex offenders were being sent to prison as sentence lengths "better reflect the severity" of crimes like domestic violence, rape and child abuse.

She rejected calls by Labour officials to reduce the number of prisoners in England and Wales by half, warning that such a move would be "reckless" and "endanger the public".

Ms Truss said courts needed to be given the right tools to intervene before prison was an option.

"There can never be an excuse for committing crime but too often people end up in prison because our interventions to tackle problems like drug addiction or mental health issues don't work as well as they should," she added.

"Community sentences are most effective when they tackle the problems that contribute to the offender's crime."

Image copyright PA Image caption Justice Secretary Liz Truss wants to cut prisoner numbers by reducing reoffending

The justice secretary said the Prison and Courts Bill - due to be published this month - will "enshrine in law that reforming offenders is a key purpose of prison and that the Secretary of State has a responsibility for delivering it".

"This will usher in the biggest reform of our prisons in a generation. It will transform our prisons from offender warehouses to disciplined and purposeful centres of reform," she added.

After her speech, Ms Truss said she would be meeting with the family of Dean Saunders, who died in Chelmsford Prison after he was found electrocuted in his cell.

Andrew Neilson, spokesman for the Howard League for Penal Reform, said the justice secretary needed to act to get prison numbers down quickly.

"She wants to reduce prison numbers in a long-term way through tackling reoffending but she won't look at sentencing reform to actually try and get numbers down quickly," he told the BBC.

"And I'm afraid that without that sentencing reform we are going to continue to have ministers making similar speeches bemoaning the violence and the deaths in prisons because we will not get a solution without doing something about prison numbers."