“Passengers should not travel to the airport under any circumstances until the airport reopens.”
London Fire Brigade said there has been a “significant” fire at a substation in Hayes, a town in the London borough of Hillingdon.
“The fire has caused a power outage affecting a large number of homes and local businesses, and we are working closely with our partners to minimise disruption,” said assistant commissioner Pat Goulbourne.
He said the fire was first reported at 11.23pm (11.23pm GMT).
“This is a highly visible and significant incident, and our firefighters are working tirelessly in challenging conditions to bring the fire under control as swiftly as possible.”
British utility firm Scottish and Southern Electricity Networks said on its website that an “unplanned outage” had left more than 16,000 homes without power in the area.
80m passengers a year
Heathrow handles more than 80 million passengers a year and the operator says there are around 1300 takeoffs or landings a day.
The website FlightRadar24 reported a number of diversions already, including a Qantas flight from Perth, Australia, sent to Paris, and a United Airlines flight from New York, which will land in Shannon, Ireland.
In January, the Government gave permission for Heathrow to build a third runway – which could be ready by 2035 – after years of legal wrangling brought on by complaints from local residents.
Five major airports serve the capital and towns nearby.
But capacity is stretched, especially at Heathrow whose two runways each measure almost 4km in length, while the airport covers a total area 12.3sq km.
It opened in 1946 as London Airport before being renamed Heathrow, a hamlet demolished two years earlier to make way for the construction.
Situated 25km (15 miles) west of central London, the present Heathrow serves 200 destinations in more than 80 countries, with passengers having access to four terminals.
Among its main flight destinations last year were Dublin, Los Angeles, Madrid and New York.
