Update (12.06pm): The four have now been released.
Four PSM members were detained on the way to a gathering at Teluk Rubiah in Perak this morning.
The four – Choo Chon Kai, Nagen, Patrick and Alex – were on the way to a gathering to express concern about the RM4bn Vale trans-shipment project in Manjung.
The gathering took place at 10.30am but the four were stopped at a police road-block on the way to venue.
They have been taken to the Manjung District Police Headquarters.