Extinction Rebellion protesters have tried to storm the new BBC building in Cardiff city centre.
Protesters have been holding a demonstration in Central Square between the new BBC Wales headquarters and Central Station.
There are reports that some of the protesters have glued their hands to the building and police stopped others from entering.
It comes a day after they blocked Bute Terrace in both directions and caused traffic delays around the city.
Around 400 people are estimated to have attended the protest, which is part of a week-long campaign across the UK.
A spokesman for South Wales Police said: “Officers are currently in attendance at a protest in Central Square in Cardiff. One person has been arrested on suspicion of committing criminal damage.
“Officers are working to engage with protest organisers and attendees in order to remind them of their obligations under the current Coronavirus legislation and the overarching goal for everyone to take personal responsibility by following Welsh Government regulations toKeep Wales Safe.
Extinction Rebellion held a socially-distanced ''beach party'' on the steps of the Senedd to highlight the threat of climate change on weather patterns and rising tides.
They claim most of Wales' capital city could be underwater within 80 years unless urgent action is taken to combat climate change.
BBC Wales begun broadcasting live from its new headquarters in July.
It announced 60 jobs are to be cut in June as it tries to make £4.5m in savings this financial year.
In London, climate change protesters from the group glued themselves to the ground around Parliament during a third day of disruption in central London.
Some Extinction Rebellion supporters said they “jumped the barriers and ran past armed police to glue (themselves) on to the floor outside the House of Lords”.
The tactic, a staple of previous protests, was accompanied by scores of others staging a sit-in elsewhere around the perimeter of the parliamentary estate, including at the Carriage Gates.