Image copyright Facebook Image caption Ciarán Maxwell was arrested after searches in Larne, County Antrim, and Devon

A serving Royal Marine, arrested in Somerset as part of an investigation into Northern Ireland-related terrorism, is still being questioned.

Ciarán Maxwell, 30, from Larne, was detained by officers from the Metropolitan Police Service's Counter Terrorism Command on Wednesday.

It is understood the operation is connected to the discovery of two arms dumps near Larne earlier this year.

They were suspected to be linked to dissident republican paramilitaries.

Mr Maxwell was arrested after searches in Larne and Devon.

The operation involved several UK police forces, including the Police Service of Northern Ireland (PSNI).

It is understood MI5 is also involved in the operation in England which is likely to continue all weekend.

You can follow the latest developments on the police investigation at the BBC Devon and Cornwall live page.

Media playback is unsupported on your device Media caption Ch Insp Antony Hart gives details of the arrest and searches

Following the arrest on Wednesday afternoon, police in Devon searched a house in Exminster and a wooded area nearby.

The PSNI searched at least two houses on the Old Glenarm Road in Larne.

It is understood that a number of laptops and mobile phones were seized from the houses as part of the investigation.

A woman, who said she was the aunt of Ciarán Maxwell, expressed fears for her family's safety following his arrest.

She said the family only became aware this afternoon that police searches were being carried out.

The wider family are believed to be well known in the town.

Significant arms cache

In March, the PSNI said they had uncovered a "significant terrorist hide" of bomb-making components and explosives at Carnfunnock Country Park.

Among the items recovered were wiring, circuit boards, partially constructed power timer units and a small quantity of explosives.

In May, a second significant arms cache, including an armour-piercing improvised rocket and two anti-personnel mines, was found at Capanagh Forest, near Larne.

Image caption Forensic investigators were involved in the Larne searches

'Intelligence-led'

Mr Maxwell is suspected of being involved in preparing for acts of terrorism and is being held at a West Country police station.

Police said the operation was pre-planned and intelligence-led as part of a collaboration between the Met, the Police Service of Northern Ireland and the South West Counter Terrorism Intelligence Unit.

The arrest was the culmination of months of police work, said BBC News's home affairs correspondent Daniel Sandford.

Media playback is unsupported on your device Media caption NI terrorism: Royal Marine arrest in Somerset was 'pre-planned'

The arrest was made at 12:20 BST by Met detectives supported by officers from Avon and Somerset and Devon and Cornwall Police.

At the suspect's home town in Larne, heavily armed police supported forensic investigators as they searched houses on the Old Glenarm Road.

Army technical officers, who are routinely deployed where there is a threat of explosives, were also involved in the operation.

Media playback is unsupported on your device Media caption Police searches in Larne follow the arrest of a Royal Marine over Northern Ireland-related terrorism

BBC News NI reporter David Maxwell said he saw officers bringing a ladder into one of the houses, while bags of material were taken in and out of the properties.

Devon and Cornwall Police said they will be carrying out patrols to try to reassure the community following the anti-terrorism operation in Devon.

The force said there was no intelligence to suggest a threat to the community.

A Ministry of Defence spokesman said: "We are aware of a police investigation involving the arrest of a member of the armed forces under the 2000 Terrorism Act and will assist this investigation fully.

Image caption Searches in Devon focused on a house in Exminster and a wooded area nearby

"It would be inappropriate to comment further on an ongoing investigation."