Police have been told to put all samples from suspected drink drivers on ice after forensic scientists withdrew testing services.

A leaked memo to all chief constables revealed staff at the Forensic Science Service have stopped processing motoring cases.

They have been told to instruct staff to refrigerate all blood and urine samples as officials urgently try to find a private company to take on the workload.

The National Policing Improvement Agency (NPIA) memo said the FSS will not process any samples taken under the Road Traffic Act from today onwards.

It said officials hope to find "alternative suppliers" within seven working days and urges forces not to make their own arrangements.

The memo added: "We appreciate the challenges and difficulties that this change may cause your force. However, we would ask that you continue to work with us whilst we resolve this issue."

The move affects cases where suspected drink drivers opt for a blood test, are unable to provide a breath test or police equipment is faulty.

It comes almost two months after the Government announced the loss-making FSS will be wound down by March next year.

Wiltshire Deputy Chief Constable David Ainsworth is leading a behind-the-scenes team, dubbed Operation Slingshot, tasked with managing the demise of the FSS.

It is working with officials from the Association of Chief Police Officers, Home Office and the NPIA.

The FSS undertook 16,099 laboratory tests on blood and urine samples in 2009, according to a report by Sir Peter North published last year.

It is understood the Government and senior police officials were warned in December that the FSS would stop handling drink driving samples within weeks.

The FSS had originally planned to close its sample testing base at a laboratory in Chorley, Lancashire, as part of cost-cutting measures.

Officials wanted to transfer equipment and retrain staff to take on the work at its base in Lambeth, south London.

But after ministers announced the FSS would be shut down, officials decided to abandon the plan. The Chorley centre will close next month.

The FSS, which employs around 1,650 people and has been owned by the Government since 2005, was said to be losing around GBP2 million every month.

But the decision to close it met widespread opposition with more than 24,000 people signing an online petition against it.

One union said the move made a mockery of the criminal justice system and would destroy a "world class" body that it the envy of police overseas.

Investigators at the service have contributed to the successful prosecution of Ian Huntley, Suffolk Strangler Steve Wright and paedophile Roy Whiting.

Speaking in December, Deputy Chief Constable Chris Eyre warned the end of the FSS would have "significant implications" for all police forces.

Alan Jones, who is responsible for roads policing at the Police Federation, said: "If this is true then it is diabolical and this must be urgently addressed.

"It sets back all the good work achieved to deter drink and drug driving and is not helping frontline policing."

A statement released on behalf of Acpo and the NPIA said: "As part of the managed wind-down of the Forensic Science Service a number of services currently delivered to police forces will be discontinued.

"There is capacity to undertake these services by other forensic suppliers under the NPIA's national framework for the supply of forensic services to policing.

"A transition plan was already in place for the transfer of the testing work undertaken by the Forensic Science Service.

"Swift arrangements will now be made to ensure that alternative suppliers provide the analysis for Road Traffic Act drink and drug cases. There are already other forensic suppliers who undertake this work.

"A small number of samples may be held by police forces whilst the new arrangements are put in place quickly, but this will have no impact on the criminal justice process.

"The transition arrangements for the work of the Forensic Science Service is being co-ordinated by a national team comprising NPIA, ACPO and Home Office to ensure there is no impact on operational policing."