Hundreds of commuters were stuck on trains into London in Monday morning’s rush hour following a trackside fire.
Trains to Paddington and Heathrow in the west of the capital were being held up for more than an hour from around 6.45am, passengers said.
National Rail said the disruption was caused by a fire between Acton Main Line and London Paddington, and trains were expected to be disrupted until the end of rush hour at 9am.
Routes run by Great Western Railway (GWR) and Transport for London (TfL) have been affected.
TfL said no passengers have been injured or evacuated, and operators are waiting for the fire service to confirm it is safe for journeys to resume.
It tweeted earlier: "There's a line side fire in the Paddington area, all is being done to restore the service. But we have to wait until all clear is given by the fire services."
GWR said 12 trains had been cancelled and many more delayed.
It tweeted earlier: "Following a fire next to the track between London Paddington and Heathrow Terminal 5, all lines will be reopened shortly. Train services running to and from these stations may be cancelled, delayed or revised."
