National Rail says passengers are set for a day of disruption due to a recurring signalling fault at Manchester Airport.
Northern, TransPennine Express and Transport for Wales services are all affected between the airport and Manchester Piccadilly.
Some trains are running late, while others are being cancelled this morning as a result.
National Rail first reported a signalling issue before 6am.
The issue has since reoccured, with railway bosses warning passengers of all-day disruption after 7.15am this morning.
Updates will be posted in this blog.