The announcement comes despite evidence showing inspection and enforcement activity is the most effective way to ensure that employers comply with health and safety laws.
The TUC's biennial survey of safety reps finds nearly one in 10 reps (9%) say that the last inspection at their workplace was more than three years ago, while a further 15% say it was between one and three years ago. Only quarter (27%) say their workplace has received a visit within the past 12 months.
In small companies that employ fewer than 50 people only 16% have had an inspection in the past year. Even among large workplaces with over 1,000 workers, only one third have been inspected within the past 12 months.
The proportion of employers who make some improvements because of the possibility of an inspection has jumped up to 61% from 52% in the last survey, and two thirds of employers do more than the minimum to comply with a legal enforcement notice.
TUC general secretary Brendan Barber said: "Knowing that an inspector is likely to visit is one of the key drivers to changing employers' behaviour and making the workplace safer and healthier.
"It is a scandal that nearly half of workplaces in the UK have never been visited by a health and safety inspector.
"More than a million workers are currently suffering from an illness or injury caused by their work, and in 2009 over 30 million days were lost due to work-related sickness absence. This time off work cost employers £3.7 billion – yet much of this could have been prevented if they had ensured their workplaces were safe.
"Deep cuts in spending will make it easier for employers to avoid their obligations under the law to protect their staff at work. The Health and Safety Executive has just seen its government funding cut by 35% and that – combined with a 28% cut in local government funding – will have a very damaging impact on safety in UK workplaces."
