An antisocial behaviour team has promised extra security for diaries written about nightmare neighbours after a blunder by council workers led to 40 books being delivered to the wrong home.

Oxford City Council launched an investigation after incident diaries written by a neighbour reporting antisocial behaviour were accidentally delivered to the family they were monitoring.

All incident diaries will now be stored in sealed, addressed bags.

The diaries are used by the council's crime and nuisance action team (Canact) to help gain antisocial behaviour orders and evictions.

The inquiry was launched after 40 diaries were delivered to the wrong address in Sawpit Road in Blackbird Leys in October.

Council spokesman Louisa Dean said: "We have carried out an internal investigation following this incident and have tightened up procedures.

"We have also put in place a procedure for the movement of Canact's confidential documents to others outside the council to ensure that they do not fall into the wrong hands.

"Diaries are an effective method for providing evidence in court and we want people to continue using them."

Neither family involved in the diary blunder wanted to comment on the incident.

The Independent Working Class Association (IWCA) called for a more thorough investigation into the blunder.

City councillor Lee Cole said the inquiry already carried out had failed to identify who was to blame.

"Somewhere someone has made an almighty cock-up," he said.

"We need an investigation to show who is to blame, not this vague uninformative report."

The council report on the incident also revealed that most such diaries proved useless in court because neighbours were reporting mundane day-to-day events rather than crimes and antisocial behaviour.

The city council has issued 48 incident diaries for residents to report antisocial activity in the past year but only 12 were used in court. In future, residents are to be advised on how to complete the books correctly to help secure convictions.