Suffolk Constabulary has confirmed it is among a number of police forces affected by an issue surrounding drug-driving test analysis.

An investigation is underway into concerns over the accuracy of analysis by forensic laboratory, Synlab.

The scale of the problem has yet to be confirmed, but the prosecution service is understood to be reviewing affected cases.

At least one driver's conviction has been reopened and withdrawn in Cumbria, it has been reported.

The issue concerns the analysis of samples tested in one specific toxicology lab for cannabis metabolite delta-9-tetrahydrocannabinol (THC) – and was detected as a result of an information request by a defence scientist in relation to a case.

Synlab voluntarily suspended accreditation for Section 5A Road Traffic Act testing.

The National Police Chiefs’ Council (NPCC) said it is working with the Forensic Science Regulator’s office to understand the impact of the issue.

NPCC lead for forensics, Chief Constable James Vaughan said 23 forces were directly affected across England and Wales.

A Suffolk Constabulary spokesman confirmed it was among the 23 forces and would be working closely with the Crown Prosecution Service.

Synlab said it was committed to the highest quality in testing and diagnostic services.

A spokesman added: "We undertake more than 45 million tests in the UK and Ireland every year and, although issues are rare, we take any concerns raised extremely seriously.

"We are very sorry that there has been an issue with the THC testing service we provide within one of our specific toxicology laboratories, and we apologise to anyone affected.

"As soon as concerns were raised, we took immediate steps to remedy the situation, including voluntarily suspending our UKAS accreditation, which was later confirmed by UKAS.

"We are always keen to learn and to improve, and have been working with regulators and other partners to support a thorough investigation.

"We responded swiftly to address the findings of UKAS inspectors and are presently undergoing assessment for our reaccreditation, which we expect to have reinstated in August 2021.

"Please be assured that this issue is limited to one specific service within the only forensic laboratory where we undertake cannabis (THC) testing for Road Traffic Act cases.

"Anyone with any queries can email contactus@synlab.co.uk."