Two people were arrested after pro-refugee protesters clashed with police outside St Pancras station.
Some demonstrators allegedly threw smoke bombs at officers on Saturday night as activists stormed police lines at the rail hub, where Eurostar trains come in to London.
Dozens of protesters, many clad in black and with hoods up and their faces obscured with scarves, breached police barriers at around 6pm.
Scotland Yard said they tried to enter the Eurostar platforms at the station but were stopped by officers.
A video posted on Twitter shows dozens of activists pushing their way through the police lines and swarming into the station.
The British Transport Police (BTP) said a woman and man were arrested during the clashes.
In a statement the force said: "At around 6pm on Saturday 24 October a number of protesters arrived at St Pancras rail station and officers worked to facilitate a peaceful protest.
"Around this time a number of other individuals arrived at the station causing disorder, and missiles, including smoke bombs were thrown at police officers.
"A woman was arrested on suspicion of assaulting two police officers and a man was arrested on suspicion of a public order offence."