DOZENS of drug drive cases involving the region’s police forces are under review after toxicology results at a laboratory were allegedly interfered with.

Two men have been arrested on suspicion of perverting the course of justice over what has been described as the “manipulation of quality control data”.

The probe into failures at Manchester-based Randox Testing Services could have major implications with approximately 484 cases across the country now under review to see if prosecutions were wrongly pursued.

Cleveland Police said 28 cases involving the force were being looked at, while it has been reported that North Yorkshire has 63 cases under review.

Durham Police said it had a number of cases, but the exact figure was still to be determined.

Northumbria Police would only say that a “small number” of results relating to the force had been affected.

A Cleveland Police spokeswoman said: “We are working closely with our Crown Prosecution Service (CPS) colleagues to investigate which cases may be affected by the quality issue at Randox.

“We are looking at 28 cases. However the number may reduce as we delve deeper into the individual circumstances.

“The circumstances of the quality failure are being investigated and a criminal inquiry has been launched by Greater Manchester Police.”

A spokesman for Northumbria Police said it was also working closely with the CPS to review cases where a quality issue could have played a part in a prosecution.

He said: “We will be speaking to anyone whose case may have been affected.

"It is essential we maintain the quality and integrity of the assessment of any forensic evidence we seek to use in furthering our protection of the public and will be working closely with our forensic service providers to ensure this is the case."

Randox Testing Services describes itself as a global market leader in the forensic toxicology and drug and alcohol testing industry and states that half of all UK police forces send forensic samples to it for testing.

It reported the matter to police following an internal investigation and has said there is no evidence that samples were subject to interference.

Chief Constable Debbie Simpson, the National Police Chiefs’ Council Lead for Forensic Science, said: “We have been made aware of a quality failure with Randox Testing Services.

“Randox has provided each force with a list of cases that could have been affected. We have provided guidance to forces so they are able to review each case to determine if compromised data played a part in prosecution and the CPS will then take appropriate action in any cases identified.

"While the investigation is ongoing, we are working with a number of forensic service providers and the Forensic Science Regulator to ensure that any requirement for forensic services is dealt with in the normal timeframes."

A spokeswoman for Greater Manchester Police said the two men arrested, a 47-year-old and a 31-year-old, had been bailed pending further inquiries.

She said: “Our investigation concerns the manipulation of quality control data around sample analysis.

“We do not have any information or evidence to suggest that samples themselves have been directly tampered with.”

The CPS said it was assessing the impact of the issue and working with other agencies to decide what action should be taken in relation to affected cases.