Inspectors, scientists and other professionals represented by Prospect will join administrative and managerial staff from the Public and Commercial Services Union (PCS) in the one-day strike on Monday 29 March. The strike action will be followed by a work-to-rule.

The offer tabled by the executive will result in its most experienced staff receiving a 1.5% pay rise this year. The unions calculate that HSE has 3.7% of its paybill to spend, while the cost of the unions’ claim is only 3.3%.

Prospect negotiator Richard Hardy said: "To offer the most experienced inspectors in HSE only 1.5% is derisory. Morale in HSE is low enough as it is, without forcing our members to take pay cuts.

"We are very worried that members will vote with their feet, stripping HSE of hundreds of years of experience which will have an horrendous impact on workplace safety throughout the UK. Our members are striking to protect the health and wellbeing of other workers in their workplaces. All we want is a fair settlement."

PCS negotiations officer Steve Farley added: "Our claim for a minimum 2.6% increase is both reasonable and affordable and would ensure staff do not suffer pay cuts when compared to inflation. Despite 11 months of talks with HSE, management has refused to improve on a deal which will see our members’ pay cut over the next three years."

Major incidents and court cases will be given dispensation from the strike action. Richard Hardy stressed: "Our members are not putting safety at risk. It is the actions of HSE management in imposing pay cuts on our members that have forced us down this avenue."

Prospect and PCS members will be picketing HSE offices at Plymouth, Poole, Bristol, East Grinstead, Basingstoke, Ashford, Central London, Chelmsford, Luton, Norwich, Northampton, Nottingham, Sheffield, Leeds, Newcastle upon Tyne, Edinburgh, Aberdeen, Glasgow, Carlisle, Preston, Manchester, Bootle, Newcastle under Lyme, Birmingham, Worcester, Cardiff, Carmarthen and Wrexham.

The unions will be holding press conferences at 10am on Monday March 29 at Prospect’s London headquarters, 75-79 York Rd, SE1 7AQ, and itsLiverpool office at 6 Anson St.