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.
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One-year-old sheepdog Nell was stolen from a farm on the outskirts of Dolgellau.
Police are investigating an allegation that a young child was approached by a stranger in Llanelli.
An unsettled few days are in store, with rain and wind expected.