Trains could be delayed along Weymouth to London Waterloo route.
Passengers have been warned South Western Railway (SWR) services may be affected due to problems at Brockenhurst.
Due to the signalling problem, trains may have to run at a reduced speed through Brockenhurst station.
Disruption is expected to last until the end of the day.
A spokesperson for SWR said: “We have been informed that there is a signalling problem at Brockenhurst. This means that trains may have to run at a reduced speed through this station.
“For further information or onward travel advice please speak to a member of staff or use a station help point.
“We are very sorry for any delay that this may cause to your journey.”
Due to a signalling problem at London Waterloo some SWR lines are blocked, however this is not currently impacting services to and from Weymouth.
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