Commuters are facing severe disruption across the London Underground after an extreme heat warning was put in place.

Transport for London has issued delay warnings to 12 different lines as rush-hour commuters face chaos travelling home.

Earlier today, a train derailed in East Sussex, forcing the closure of several rail lines.

Police, fire crews and ambulances were called to the scene near Lewes rail station just after 3.30pm.

Major delays are now expected until 10pm, according to National Rail.

This comes after commuters were told ‘not to travel’ after forecasts of 38°C temperatures.

Currently, the TfL website says that the Central, Elizabeth, Mildmay and Picadilly line has severe delays, while the District is part suspended.

The fifth heatwave of the year is underway with Met Office extreme amber heat warnings now active until midnight due to the scorching weather front.

Across the UK, ,pdes pf transport from roads to trains are being put under extra pressure.

London, the southeast, east of England and the East Midlands are set to bear the brunt, with temperatures remaining high for the rest of the week.

Heat health alerts are also in place, covering all of England as temperatures are likely to affect wellbeing.