Judges are to get powers to prevent the early release of dangerous criminals as part of new sentencing measures announced today.

Under current guidelines, both dangerous and non-violent offenders are automatically freed from jail halfway through their sentences and are then supervised in the community by probation officers.

Judges can also reduce the minimum jail term to be served by a dangerous offender in return for an early guilty plea.

The home secretary, John Reid, today set out plans designed to ensure that judges impose tougher sentences on dangerous criminals.

His proposals have been seen as a populist measure in the wake of public alarm over the case of Craig Sweeney, who could be released on parole just over five years after he abducted and sexually abused a three-year-old girl.

Judges will be given more discretion to say how long they think offenders should spend in prison, while offenders posing a serious risk to the public will no longer be released halfway through their sentences.

In addition, the Home Office sentencing guidelines council will say whether judges should give sentence discounts to people who plead guilty.

"Courts should be rigorous in applying their powers to protect society against dangerous and violent criminals," Mr Reid said.

"We need to strengthen judges' hands so they have greater discretion to impose even tougher sentences on offenders they believe pose a very serious risk.

"The measures we are putting forward today are designed to ensure the public are better protected from dangerous offenders and that resources are targeted at those offenders who pose the most significant risks."

In June, Sweeney was sentenced to life for abducting and sexually assaulting a three-year-old girl, but will be eligible for parole after five years.

The 24-year-old attacked the girl in January, weeks after his prison licence for a sex attack on another child ran out. He was sentenced to life but given a discount for his early guilty plea, receiving a minimum tariff of five years and 108 days.

The trial judge was criticised, but he was working to rules set by the Home Office and sentencing guidelines council allowing discounts for guilty pleas.

Today's proposals will grant judges the ability to override those rules, which were introduced two years ago by the former home secretary David Blunkett.

Speaking prior to today's announcement, Paul Cavadino, the chief executive of the crime reduction charity Nacro, said: "Judges should have discretion over how much discount to give for a guilty plea.

"Offenders who plead guilty early and save witnesses the trauma of giving evidence should receive a greater discount than those who admit their guilt at the 11th hour."

However, he said automatic release under supervision after half the sentence should be retained for the majority of prisoners.