It's over recent Census results, which showed a decline in the number of Welsh speakers.
The Welsh Government say the building remains open to staff and visitors as usual.
Cymdeithas are holding a peaceful protest at one of the entrances at the Welsh Government offices in Cardiff. The main reception remains open as usual to all staff and visitors.
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Andrew Price joins South Wales Caving Club to venture into the deepest cave in the UK
Any drizzle this afternoon will subside to leave a largely dry evening. Clearer skies in the north overnight.
Police were called to several Tesco stores in Wales to deal with chaos at midnight. Huge numbers hunted for bargains in shops and online.