Met police officers arrested a 34-year-old man from south-east Kent, a 58-year-old man from west London and a 36-year-old woman from South Yorkshire on suspicion of inviting support for a proscribed organisation, contrary to section 12 of the Terrorism Act 2000, during a protest at Victoria Embankment on Saturday.
They were arrested at approximately 16.00hrs and taken into custody at a West London police station.
A fourth person, sought by police was subsequently arrested on Sunday, 14 January when vigilant Met police officers spotted him amongst those taking part in a protest against the counter-terrorism arrests outside a West London police station.
Officers arrested the 49-year-old from south London on suspicion of inviting support for a proscribed organisation at approximately 15.00hrs.
All four people have been bailed to return to a west London police station in late March.
Police have completed searches of four addresses in south-east Kent, South Yorkshire, west London and south London.
Met Counter Terrorism Command detectives worked with policing colleagues to detect and deal with suspected terrorism offences across the weekend.
This new investigation is one of around 30 launched by the Met Counter Terrorism Command into suspected criminality at protests – the majority of which relate to potential terrorism offences.
Commander Dominic Murphy, head of the Met Counter Terrorism Command, said: “The vast majority of people attending protests are doing so peacefully. There are consequences for those who are not and where officers see people supporting proscribed organisations we will take action, as we did this weekend.”
