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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It's hoped more people will consider using their local service amid concerns over the future of the bus industry.
Dry across the country this evening with broken cloud and some late sunshine. Scattered showers expected tomorrow.
40,000 people are expected at the motorbike event in the capital this weekend.