The number of construction workers who were killed in accidents rose by 25 per cent last year, according to a study for Ucatt, the construction union.
The Health and Safety Executive (HSE) has estimated that in 70 per cent of cases management failure contributed to or caused the death of the construction workers, yet the Ucatt study reveals that the number of convictions of companies where death has occurred has fallen by 75 per cent.
Alan Ritchie, the Ucatt general secretary, said that the HSE's failure to prosecute was "profoundly shocking".
But Geoffrey Podger, chief executive of the HSE, told the BBC: "Every prosecution has to be considered on the circumstances of the case - is the evidence available? Does it support a prosecution? Is it in the public interest?
"And actually our overall rate of prosecution is going up, it's not going down, and we are, as far as we're concerned, a regulator with teeth and we're quite prepared to use them in this sector."
The study has been published to mark Workers Memorial Day on April 28th.
