All trains running between East Croydon and Oxted have been cancelled until further notice due to a landslide.
Services to South Croydon, Sanderstead, Riddlesdown and Upper Warlingham are among those disrupted by the landslip, which happened between Woldingham and Oxted this morning.
The line between South Croydon and Oxted has been closed completely.
Network Rail engineers are on-site but no estimated time for the line to reopen has been given.
Southern Rail advised passengers travelling to and from Sanderstead to use Purley Oaks station instead and passengers to and from Upper Warlingham to use Whyteleafe station.
The company is operating rail replacement buses between Oxted and Redhill.
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