Murder, rape and drug driving offences are among more than 200 cases in Suffolk and Norfolk where convictions could be jeopardised due to suspected manipulation of forensic evidence.

Suffolk Constabulary has 92 cases which have been affected by the issues relating to Randox Testing Services in Manchester, while Norfolk has 117, police have said.

A total of 42 police forces across the country sent data to the laboratory for testing.

The National Police Chiefs' Council (NPCC) said that of the 10,000 cases that could have been affected, 75 per cent were traffic offences, such as drug driving. Other cases included violent crime, sexual offences and unexplained deaths.

So far, retests on samples involved in sexual offence cases, violence or homicide have showed no change.

The NPCC looked into Randox Testing Services in Manchester after two men were arrested on suspicion of perverting the course of justice in February.

Re-tests will have been carried out on 1,500 cases by the end of the year.

It is understood Suffolk and Norfolk police are still waiting to learn the significance of this, but no formal appeals against convictions have been lodged.

A force spokesman confirmed that of the 92 cases affected in Suffolk no cases have yet been adversely affected, but re-testing will continue 'with the most serious cases prioritised'.

He added: 'Norfolk Constabulary has 117 cases which have been affected by the issues involving sub-contraction of toxicology testing to Randox Testing Services.

'This includes investigations ranging from murder to rape and drug driving offences.

'A number of tests have been carried out and, to date, no cases have been adversely affected.

'The Constabulary is taking this matter very seriously and the response to the situation is being actively managed by a team led by a senior officer and including a range of experts from both the police and Crown Prosecution Service.'

In February Randox Testing Services, which is part of the Northern Ireland-based Randox Laboratories group, said it was treating the matter with the 'utmost seriousness'.

At the time, police said 484 cases handled by the firm since November 2015 could be affected.