Met officers say no immediate indication of foul play as airlines around the world face days of disruption

• Heathrow airport closed – live updates

Counter-terror police are leading the investigation into the “unprecedented” electrical substation fire that has closed down London Heathrow, stopping more than 1,300 flights, as engineers tried to restore power to the airport on Friday.

Airlines face days of disruption with hundreds of thousands of scheduled passengers already unable to fly in and out of Europe’s busiest airport, after what ministers said was an “unusual and unprecedented incident”.