The survey showed that the recruitment sector was the worst offender with abuse at 66% above average, followed closely by the office equipment sector at 41%.

Health and beauty sectors, utility, and government sectors, were also singled out as performing above average with results recorded at 33%, 23% and 23%, respectively.

DQM Group found that annual marketing budgets had been revised down to the greatest extent ever in the survey's nine-year history.

It said that with budgets tightening, but the need for new business higher than ever, marketers could be ignoring list licence terms in order to 'over mail'.

DQM Group chief executive Adrian Gregory said: "Rigorous policing of lists has to be maintained, especially if marketers are turning to desperate measures in these economically difficult times."

Associations and societies were recorded as being top performers, despite being labelled the worst offenders in 2006. Other good performers included property services and travel, all of which remained under the all-sector average.

"If list owners continue to experience a rise in abuse, they will continue to lose revenues, and may consider withdrawing their valuable data from the market. Consequently marketers will find it increasingly difficult to obtain good quality data as a result," Gregory said.

"We should all be concerned too about the impact of list abuse on the wider direct mail industry at a time when data security, ID theft, data quality and privacy are the focus of consumers, environmentalists, media and legislators alike," he added.