A four-metre-deep sinkhole opened up underneath railway lines in south London on Monday, causing travel chaos for commuters, who were advised to avoid one of the capital’s busiest stations just as the evening rush hour was getting under way.

Network Rail said it was moving more than 50 tonnes of ballast to the scene in Forest Hill to try and shore up the track, but said travel problems could last until the end of the day.

The hole shut down two lines into London Bridge station and severely disrupted, diverted or cancelled many Southern train services into and out of the station. The problems hit within days of Southern having to release a reduced timetable because it was struggling to deliver services as expected.

Passengers were told to use either nearby Victoria or Blackfriars stations. A Network Rail spokesman said: “Our aim is to have the railway fixed for tomorrow morning, but holes like this can be unpredictable. Until the ballast is packed into the hole, we won’t know for certain if the hole is stable or not – so passengers are advised to check before they travel.”