Lines have now reopened following an earlier trespass incident between Southampton Central and Fareham.
As service recovers, trains may still be cancelled, delayed by up to 30 minutes or revised.
Southern services are no longer affected by this disruption.
Disruption is expected until the end of the day.
Customer advice:
South Western Railway
For further information or onward travel advice, please speak to a member of staff or use a station help point.
Check before you travel:
You can check your journey using the National Rail Enquiries real-time Journey Planner
Compensation:
You may be entitled to compensation if you experience a delay in completing your journey today. Please keep your train ticket and make a note of your journey, as both will be required to support any claim.