Commuters have been told to avoid the second-busiest train station in the UK after a major signal failure blocked most lines into and out of London Victoria.

Severe disruption has hit the network after dozens of Gatwick Express, Thameslink and Southern services were cancelled. Southeastern services to the station appeared to be unaffected.

Network Rail advised passengers not to travel via Victoria and passenger information boards at the station showed a slew of cancelled services.

Good luck if you’re using London Victoria this morning. Kent trains fine but everything else hit by a major signal fault pic.twitter.com/FuFQZtlmpx — Andy Ivy (@andyivy) July 5, 2018

A signal fault in the Streatham area has been confirmed as the source of the disruption. A problem with the equipment was discovered at 10.30pm on Wednesday, and Network Rail engineers were unable to fix it in time for the Thursday morning commute, despite working overnight.

About 210,000 passengers use London Victoria each day. Replacement buses are operating at “key locations”, but these will be subject to availability as many are already in use to take children to school.

A Network Rail spokesman said: “Owing to a loss of signalling at Streatham Common, services are being disrupted to and from London Victoria. The signal loss means we are unable to run services between Balham, Selhurst and Haydons Road.

“We have had engineers working on site overnight doing all they can to fix the problem. However, we anticipate that the signalling will not be up and running this morning.

“We apologise for the inconvenience caused by the fault and passengers are being advised not to travel with Thameslink, Southern or Gatwick Express from the south into London this morning.”

Thameslink passengers have already suffered weeks of disruption after the introduction of new timetables on 20 May. The company advised commuters not to travel into London from the south and warned of knock-on delays affecting services into London from the north.

⛔️No service on the Wimbledon/Sutton loop



⚠️ Limited service on the Brighton Mainline - services that are running are extremely busy.



Advice remains do not travel from the South into London if poss.



More info & alternatives 👉 https://t.co/m2dIo0sslI#TLUpdates https://t.co/Mp9hl3TGI5 — Thameslink (@TLRailUK) July 5, 2018

Trains from St Albans travelling south of London are subject to delay, cancellation or diversion due to signal failure on the Victoria line. Please use alternative travel with mutual acceptance, if travel is essential ^Ebs — Thameslink (@TLRailUK) July 5, 2018

Southern said there was no service between East Croydon and Victoria.