The home secretary, David Blunkett, yesterday set himself on a collision course with Lord Woolf, the lord chief justice, over new sentencing guidelines that could allow murderers up to a third off their prison terms in return for pleading guilty.

Responding to draft guidelines issued last September by the independent sentencing guidelines council, chaired by Lord Woolf, Mr Blunkett said he was determined that convicted murderers should "receive a punishment that reflects the unique nature and seriousness of the crime".