Due to a person being hit by a train between Rugby and Milton Keynes Central some lines are blocked.
UPDATE 13:15 - All lines have now reopened.
Emergency Services are currently dealing with the incident.
Disruption is expected on the Avanti West Coast line from Milton Keynes Central until 1pm.
A National Railways spokesperson has said: "Emergency services dealing with an incident between Rugby and Milton Keynes Central means trains running between these stations may be delayed by up to 20 minutes or cancelled."
"Due to the emergency services dealing with an incident between Rugby and Milton Keynes Central some lines are blocked. Please check before you travel," An Avanti West Coast spokesperson said, "All services between Rugby and Milton Keynes are being diverted via Northampton, adding at least 30 minutes to journeys. Despite this, some services running will still be subject to alterations and late notice cancellations."