Gardaí in Co Cork are questioning three men in connection with an investigation into fraudulent insurance claims involving tens of thousands of euro.

The three were arrested at addresses in the county bringing to 20 the number of people detained as part of the investigation.

It is the fourth phase of an investigation that has been ongoing for several months and which has been codenamed Operation Nascar by gardaí.

Detectives from the Fraud Investigation Unit based at Anglesea Street in Cork and members of the Organised Crime Unit were backed up by local gardaí when they moved on addresses in Mallow, Midleton and Newmarket.

The three men arrested are being questioned at garda stations in Macroom, Kanturk and at the Bridewell in Cork city.

Gardaí believe tens of thousands of euro have been fraudulently claimed from insurance companies through staged road crashes.

In some cases detectives believe money has been paid out on these claims, both for material damage to vehicles and for personal injuries.

They believe there is an organised crime involvement in the staged crashes and that those orchestrating them and sharing in the proceeds are connected with a subversive organisation.

One of the men arrested is being detained on suspicion of directing a criminal organisation in committing serious offences.

The arrests are regarded as the most significant to date in the operation.