Peak hour delays are due to affect all South Western Railway routes through Wimbledon station tonight.
National Rail and SWR both advised that this is due to a passenger being taken ill at the station.
As a result some London bound lines are blocked.
National Rail advised that services may be cancelled, delayed or revised as a result.
"You may be entitled to compensation if you experience a delay in completing your journey today," a post on its website read.
"Please keep your train ticket and make a note of your journey, as both will be required to support any claim."
The disruption is expected to last until at least 7pm.
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