Police closed London’s Kings Cross station as pro-Kurdish demonstrators attempted to rally inside.
Video footage showed officers guarding the station’s entrance as dozens of protesters gathered waving flags outside the doors on Sunday evening.
Hours earlier pro-Kurdish demonstrators jumped onto the tracks at Manchester Piccadilly station, forcing the station to shut.
Similar rallies have been held across Europe in support of Afrin, the Syrian city which has been besieged by Turkey for weeks.
A British Transport Police (BTP) spokesman said: “Officers were in attendance at London King’s Cross station where they responded to a number of protesters attempting to enter the station at around 5pm.
“Colleagues from the Metropolitan Police Service assisted and protesters were prevented from accessing the tracks.”
The protest caused cancellations and delays before the station reopened at about 7pm.
Protesters then moved to nearby Euston Road, bringing traffic to a standstill, and later Oxford Circus, where the London Underground station was temporarily closed at the request of police.
Turkish attack on Afrin, northern Syria – in pictures
Manchester Piccadilly station was closed for more than three hours after protestors stormed the railway lines, waving flags of various Kurdish organisations.
A spokesman for the Manchester branch of the Friends of Kurdistan solidarity group said about 400 people had gathered in the city for an international day of action in defence of Afrin. Turkey launched an offensive against Syrian Kurdish militia in the city two months ago, an operation which has been described by Kurds as ethnic cleansing.
“This is an international day of protest to break the silence of the international community which hasn’t put any pressure on Turkey to stop what it is doing,” said the spokesman. “It’s an attempt to break the silence and raise the issue in people’s consciousness.”
Superintendent Mark Cleland, of BTP, said: “While we appreciate and respect the right to peaceful protest, when this compromises the safety of the public and the protesters themselves, any offenders will attract the full investigative resources of BTP.
“Those involved in this afternoon’s incident will be subject to intense investigation with a view to arrest and prosecution.
“All protesters at Manchester Piccadilly have now been safely moved from the tracks and the station has reopened. We will continue to maintain a police presence at this station and at other stations across the rail network.”