Police working on a major counter terrorism operation linked to Pakistan said on Tuesday they had made four arrests in Birmingham.
The four men are being held on suspicion of fundraising in Britain for terrorist purposes and of travelling to Pakistan for terrorist training.
Three men aged 19 and one aged 24 were detained by officers from the West Midlands Counter Terrorism Unit at their home addresses in the Sparkhill area of the city.
Eight people arrested in September have already been charged in connection with an ongoing investigation, known as Operation Pitsford. Seven are currently on remand after appearing in court.
West Midlands police said Tuesday's arrests were pre-planned and not made in response to any immediate threat to public safety. Officers were unarmed.
Detectives have an initial 48 hours to question the suspects before charging, releasing or applying for a warrant of further detention.
(Reporting by Stephen Addison; editing by Keith Weir)