David Blunkett will today set out new sentencing principles which will mean that convicted murderers of children will face "life means life" jail terms.

The home secretary will tell MPs that terrorist murders and those involving the death of a police or prison officer in the course of their duty will result in far heavier sentences of at least 30 years, compared with the current practice of a mandatory 20-year term.

Those who murder in the course of an armed robbery will also face longer periods in prison.