Trains between Liverpool and Manchester are being delayed because of a protest on the tracks.
A number of lines in and out of Manchester Piccadilly station are currently closed because campaigners are sitting on train tracks.
The trespassers are holding banners which read "Stop Turkey from helping ISIS terrorists".
National Rail say services are likely to be disrupted until at least 3pm.
A number of trains between Manchester Airport and Liverpool Lime Street have been delayed during the protest so far.
Passengers are being warned that services may be delayed or cancelled and are being asked to check their journey before setting off.
Northern tweeted: "Due to a trespass incident at Manchester Piccadilly some lines are blocked. Passengers are advised that all lines are suspended in and out of Manchester Piccadilly.
"This is due to protesters on the track."
All services running through the station are currently delayed and Piccadilly has been closed.
