A woman has been arrested on suspicion of terrorism offences.
The 21-year-old was detained in Birmingham by officers from the West Midlands Counter Terrorism Unit on Monday as part of an ongoing investigation.
West Midlands Police say the arrest was pre-planned and posed "no risk to the public's safety".
The woman was was arrested on suspicion of preparing for terrorism acts, police said.
The arrest is part of an on-going investigation by the counter terrorism unit, where a brother and sister are currently in custody charged with terrorism-related offences.
Ummariyat Mirza, 21, of St Agathas Road, Birmingham, is charged with preparing for a terrorist attack in the UK by buying a knife and other items.
His sister, Zainub Mirza, 23, from Eastfield Road, Bordesley Green, is charged with sending Islamic State propaganda videos to others.
They were both remanded to next appear before the Old Bailey on 28 April.