The planned £1.2bn sale of NTL's radio and television broadcasting business has been dealt a potentially fatal blow after Ofcom announced tougher than expected restrictions on how the market operates. The rules, which are expected to be introduced next year, could reduce the value of the NTL business and hinder its efforts to reduce its £3.8bn debt mountain. The Nasdaq-listed cable company has said it will announce whether to go ahead with the sale of the broadcast business at the end of the year.