Prospect, the union for professionals, and the Public and Commercial Services union have described the decision as a tragedy that will disrupt vital forensic science work for police all over the country, on the day the Home Secretary has claimed the credit for a 2% reduction in the crime rate.

On behalf of 1,300 forensic scientists in the FSS, Prospect General Secretary Paul Noon said: "The government seemd determinef to out-privatise the Tories. This is macho politics at its worst. It is madness to think the criminal justice system will be better supported by an organisation driven by profit, not by public interest.

"We acknowledge the need to invest in FSS’ laboratories but Railtrack and Consignia have shown there is no guarantee that a government-owned PLC will be able to afford the required investment.

"Privatisation will inevitably lead to vital forensic work being viewed as being too costly, not carried out or undertaken in a way that undermines quality."

Mark Serwotka, PCS General Secretary, added: "These proposals are nothing short of profiteering from criminality. The plans are a double whammy for the hardworking staff in the FSS coming at time of imminent redundancies.

"Despite representations and a request for a meeting with the Home Secretary the government are hell bent on privatising what should be a public service, damaging the excellent standards and work of the FSS. Our members are vehemently opposed to this and we will be joining with other interested parties to mount a vigorous campaign against what is an unwanted and unnecessary privatisation."

Unions say the FSS is a highly effective public service that is making a huge contribution to the fight against crime and more than covers its costs. Requests for a meeting with the Home Secretary to express staff concerns over pensions, jobs and conditions and to present a number of alternative ways to raise capital have been ignored.

The review team’s main justification for the PPP option is that it would enable the £20-£30m needed to modernise facilities at the seven FSS laboratories to be raised from the money markets rather than government.

But that flies in the face of an influential Treasury report published this week, which found that the cost of raising capital is higher for a private sector owner than the government. Consequently privatisation is bound to put up costs to users, say unions.

Today’s decision will mean that Britain is the only country in the world with a privatised forensic science service.