Services at London's King's Cross and Manchester Piccadilly ground came to a halt amid demonstrations against Turkey's military offensive in northern Syria on Sunday, media report said.
Waving flags in support of a number of Kurdish organisations, the demonstrators disrupted transport networks for a number of hours, Xinhua reported.
At the time of Manchester Piccadilly's closure, British Transport Police superintendent Mark Cleland said the force appreciated and respected "the right to peaceful protest".
However, "Those involved in this afternoon's incident will be subject to intense investigation with a view to arrest and prosecution," Cleland said.
Hours later, the sudden protest in London King's Cross also forced that station to close.
King's Cross station was temporarily closed as police stopped protesters from accessing the tracks, British Transport Police said.
They then moved outside the station, blocking Euston Road briefly before heading towards Russell Square.
National Rail said Kings Cross station has fully re-opened but trains to and from there may still be delayed or revised as the service recovers, according to BBC.
The demonstrations in Britain and other parts of Europe followed several months of conflict between Kurdish groups and Turkish forces in Afrin, northern Syria.
The Kurds' supporters are angered by Turkey's assault on Afrin, which it launched on January 20 with the stated aim of dislodging the People's Protection Units (YPG), a U.
S.-back Kurdish militia that Ankara considers a terrorist group.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)