The union’s 1,220 HSE members, including inspectors, scientists and other specialist staff, will begin their strike with a co-ordinated walk-out at 1pm from HSE’s 30 offices across the UK.

Prospect members voted resolutely in favour of industrial action with 60% of respondents voting in favour of a strike, while 85% backed action short of a strike.

The dispute follows the branch’s rejection of a 1% pay offer – a cut in real terms after successive years of pay freezes and pay caps. HSE imposed the offer in November even though it was overwhelming rejected by staff.

While the action will delay on-going casework undertaken by the safety watchdog, responses to emergencies or planned court appearances will be exempt.

Prospect negotiator Jez Stewart said: “HSE staff do not take industrial action lightly. But the results of this ballot show that they have had enough of working harder than ever to see their dedication and professionalism rewarded with yet another fall in their living standards.

“In addition, pay constraint is now impacting on recruitment and retention as HSE staff vote with their feet, resulting in operational difficulties which are hampering HSE’s ability to deliver a service that the public deserves and expects.”

He said that the vote in favour of industrial action clearly demonstrates the growing dissatisfaction among HSE staff over the government’s continuing policy of civil service pay restraint.

“Our members are resolute that enough is enough and view Thursday’s action as the first step in an on-going programme of action which they plan to co-ordinate with other public sector workers and civil servants.”

Prospect had urged HSE managers to return to the negotiating table with an improved offer or risk further deterioration in employee relations among an already demoralised staff.