An 18-year-old man from Grangetown in Cardiff has been arrested on suspicion of terrorism offences.
South Wales Police say he has been arrested under the Section 5, Terrorism Act 2006 for assisting in the preparation of an act of terrorism.
Police said that today's arrest was not linked to any immediate threat to public safety.
Four men have been arrested in Cardiff by detectives investigating slavery and kidnap allegations, Gwent Police said.
An operation involving three police forces saw warrants executed at five addresses in Bristol and Cardiff this morning. Four men from the Rumney area of the Welsh capital were arrested.
Police working on Operation Imperial are probing alleged offences of slavery, forced labour, false imprisonment, kidnap and assault.
Lead officer Detective Superintendent Paul Griffiths said: "The alleged offences we are investigating are extremely serious and we would urge anyone with any information which could assist to contact the Imperial team directly."
South Wales Police has confirmed that a 22-year-old man has been arrested on suspicion of murder after the death of 45-year-old Darren Thomas, an inmate at Cardiff Prison.
Prison sources have told the Press Association the man arrested following the death of an inmate at Cardiff Prison is a serving prisoner.
It remains unclear at present what the arrested man's status is and what wing the police's investigation centres around.
South Wales Police say the death of the 45-year-old inmate is being treated as 'suspicious.'
South Wales Police says the death of a 45-year-old inmate at Cardiff Prison yesterday is being treated as 'suspicious.'
A 22-year-old man has been arrested and is in custody.
South Wales Police is investigating the suspicious death of a 45-year-old inmate at HMP Cardiff during the early hours of Thursday, March 6.
A 22-year-old man has been arrested and is in custody at Cardiff Bay Police Station.
The HM Coroner has been informed and an investigation is continuing.
A 22-year-old man has been arrested, after the death of a 45-year-old inmate at Cardiff Prison.
The Cardiff and Vale University Health Board has suspended a specialist liver surgeon linked to the "avoidable deaths" of eight patients he operated on in South Wales.
Police said a 66-year-old woman was one of two people stabbed today at a Cardiff cemetery in an apparently unprovoked attack.
South Wales Police have arrested a 25-year-old man in connection with the incident, which left the woman in hospital undergoing surgery. Her injuries are not thought to be life-threatening.
Police say a 25-year-old man arrested following two assaults in Cathays, Cardiff this afternoon remains in custody.
At 12.47pm today officers were called to Cathays Cemetery where a woman had been stabbed and this was followed by an incident around four minutes later in Tewkesbury Street where a man had also been assaulted resulting in facial injuries.
The woman is undergoing surgery at the University Hospital of Wales, Cardiff, her injuries are not life-threatening and we awaiting a further update on her condition.
Understandably the local community are shocked by what appears to be an unprovoked assault on two people.
Officers, including armed response officers, were quickly at the scene and were able to make the arrest within 30 minutes. Thankfully incidents such as this are rare, Cardiff is a safe city, the injuries sustained are not life-threatening and a person remains in custody.
At 12.47pm South Wales Police received a report that a woman in Allensbank Road has been assaulted and suffered a neck wound.
A second report was received at 12.51pm that a man had been assaulted in Tewkesbury Street.
The woman, who is in her 60s, was described as conscious and breathing at the scene and was taken to the University Hospital of Wales, Cardiff, for treatment. There is no update on her current condition.
The male victim, who is in his 30s, was described as being in shock after suffering facial injuries.
A man was arrested in Dalton Street at 1.12pm and a knife has been recovered.