Over half of criminals made to wear electronic tags on their ankles flout the terms of their curfew conditions, a review has found.
Some 59 per cent offenders ordered to be tagged by courts receive at least a warning, while more than a third are sent back to court following more serious violations, an analysis by Her Majesty's Inspectorate of Probation found.
But Chief Inspector Liz Calderbank said the most worrying finding was that in a fifth of cases where there were violations, inspectors could not even see who was supposed to be in charge.
Justice Secretary Kenneth Clarke set out proposals to extend the use of tagging in plans to radically overhaul community sentences in March.
Their use by courts has already more than doubled in the last six years, with a total of 80,000 offenders being tagged in 2010/11.