British Airways said the closure of its main hub would have a "significant impact" on its operations and customers.

"We're working as quickly as possible to update them on their travel options for the next 24 hours and beyond," it said.

Talia Fokaides, 42, was supposed to leave London on Friday morning for Athens, but rushed to Gatwick to get a new ticket when she heard the news.

Her mother was having open heart surgery later in the day.

"I just need to be there," she told AFP, her voice shaking with emotion.

Diverted

Around 120 Heathrow-bound planes were in the air when the closure was announced, according to Flightradar24.

Airport authorities said they "expect significant disruption" over the coming days.

The UK's second busiest airport, Gatwick, said it would accept some flights from Heathrow. Others were diverted to European airports including Shannon in southwestern Ireland, Frankfurt, and Paris Charles de Gaulle.

One resident near the substation said she heard a "massive explosion" as the power cut out just before midnight while another reported seeing a "bright flash of white".

Around 150 people were evacuated from nearby properties because of the fire.

London Fire Brigade deputy commissioner Jonathan Smith told reporters firefighters worked "tirelessly in challenging and very hazardous conditions".

He said the fire had involved a "transformer comprising of 25,000 litres of cooling oil fully alight" posing a hazard due to the substation's "still live high voltage equipment".

The outage left 100,000 homes without power overnight. By morning, power had been restored to all but around 4,000.

Questions

As the scale of the disruption began to emerge, Miliband faced questions about how one fire could shut down an entire airport.

He said the electricity distribution network National Grid had told him they had not seen "anything like the scale" of what happened.

"But it makes Heathrow look quite vulnerable and therefore we've got to learn lessons, as I say, about not just Heathrow but how we protect our major infrastructure," he told ITV News.

The chair of the parliamentary transport committee, Ruth Cadbury, said it was "speculative" to suggest at the moment that arson might have caused the fire.

But she told Times Radio: "There are questions about it."

Flights from all over the world were affected by the closure and aviation consultant Philip Butterworth-Hayes told AFP it would cost "certainly more than £50 million ($64.7 million)" to the airport and airlines.

Situated 25 kilometres west of central London, Heathrow's main flight destinations last year were Dublin, Los Angeles, Madrid, and New York.

- AFP

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