A Bromley man was threatened with a knife at Grove Park station last week on a train travelling from Charing Cross to Orpington.
Police were called to a report a 44-year-old man from Bromley had been threatened with a knife on Wednesday, August 13.
A British Transport Police spokesman said: "A full search of the area was carried out, but nobody was found.
"Enquiries are ongoing."
Anyone who witnessed the incident or has any other information should contact Andrew Parkes on 01689 885706.
- Rubbish on fire outside Blackfen kebab shop
- Top five must read stories
- UPDATE: Police find missing 91-year-old from Meopham
- Crystal Palace paramedic sets up life saving course
- Pensioner with dementia missing from Sidcup