Analysis by legal firm Pinsent Masons shows the average cost of an invoice has now soared to more than £700.

The controversial scheme was introduced in 2012 and allows HSE inspectors to charge contractors for visits when they break safety laws.

Fears are now growing that the HSE could be using the scheme to raise money following funding cuts.

Laura Cameron, Partner at Pinsent Masons, said: “The HSE will need to recoup the funding lost in budget cuts via wider use of the Fee for Intervention scheme.

“The regulator is issuing those guilty of breaches with invoices for increasingly significant sums- signalling that it remains serious about clamping down on non-compliance.”