Deputy general secretary Mike Clancy supported his call "before vital forensic skills are lost to the country for ever... most skilled scientists leaving FSS do not return to the profession."

When the closure was announced last December, ministers claimed FSS was losing £2m a month. But this ignored savings coming online following a transformation programme. And, according to the home affairs select committee, the costs of winding up the FSS have risen to a staggering £125m in 2010-11.

The science and technology committee's report into the closure concluded: "The government did not consider enough evidence in its decision-making. The impacts on research and development, on the capacity of private providers to absorb the FSS's market share, on the future of the archives and on the wider impacts to the criminal justice system appear to have been hastily overlooked in favour of the financial bottom line. Examining the possible impacts of a decision after the decision has been made contradicts the concept of evidence informing policy."

Three FSS labs at Chorley, Chepstow and Priory House, Birmingham, have already closed. Laboratories at Wetherby, Lambeth, Huntingdon and Trident Court, Birmingham, are winding down and will close by next April.