Travellers are facing significant disruption after Victoria station was evacuated earlier, with some trains being diverted to other London terminals.
National Rail has said trains running through Victoria may be cancelled, delayed for up to 45 minutes or diverted to London Bridge following a fire alarm which meant all trains at the station ground to a halt.
Meanwhile, a points failure at Tulse Hill has caused disruption to all Thameslink and Southern lines that go through the area.
Elsewhere holidaymakers travelling to and from Heathrow are facing disruption with the closure of the Piccadilly line between the airport and Acton Town until Wednesday.There is also disruption on the Central Line due to the continued shortage of trains.
Passengers using Thameslink were facing major disruption on Monday morning with trains being delayed and cancelled and some not serving stations in south east London but this has since cleared up with only minor delays to the London Overground between Clapham Junction and Surrey Quays.
