Police investigating extreme right-wing activity in the UK have arrested three men on suspicion of terrorism offences.

Those arrested are a 17-year-old from London, a 21-year-old from Bath and an 18-year-old from Portsmouth.

The BBC understands the investigation relates to alleged activity by a neo-Nazi group called the Sonnenkrieg Division.

Searches are ongoing at four properties in Bath, London, Portsmouth and Leeds, officers said.

Police said the arrests, made by officers from the North East Counter Terrorism Unit, were part of a planned operation.

The three men are being interviewed in police stations in London and Bath.

The 21-year-old was arrested on suspicion of possessing material useful to someone preparing an act of terrorism and conspiracy to inspire racial or religious hatred.

The 17-year-old was arrested on suspicion of encouraging terrorism, dissemination of terrorist publications, and conspiracy to inspire racial or religious hatred.

The 18-year-old was arrested on suspicion of encouraging terrorism and dissemination of terrorist publications.