Heathrow Airport is closing all day Friday because of a large fire at a nearby electrical substation that supplies it.

The airport is experiencing a "significant power outage" because of the fire, a statement from Heathrow said.

"To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23:59 on 21 March," it added.

"Passengers are advised not to travel to the airport and should contact their airline for further information. We apologise for the inconvenience."

"Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored," a Heathrow spokesperson said, adding that staff were "working as hard as possible to resolve the situation".

Passengers should not travel to the airport "under any circumstances" until it reopens, they said.

Heathrow is the UK's largest airport, handling around 1,300 landings and take-offs each day. A record 83.9 million passengers passed through its terminals last year.

The fire at the substation in Hayes, in west London, has left thousands of homes without power and caused around 150 people to be evacuated from surrounding properties.

Ten fire engines and around 70 firefighters have been sent to tackle the blaze, the London Fire Brigade (LFB) said.

A 200-metre cordon has been put in place as a precaution, and local residents have been advised to keep doors and windows closed because of a "significant amount of smoke".

More than 16,300 homes have lost power in a large-scale outage cause by the fire, energy supplier Scottish and Southern Electricity Networks said on X.

"We're aware of a widespread power cut affecting many of our customers around the Hayes, Hounslow and surrounding areas," it added.

The LFB said it had received nearly 200 calls about the fire, which broke out late on Thursday night.

Emergency services were called to the scene at 23:23. The cause of the fire is yet to be determined.

"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," said LFB Assistant Commissioner Pat Goulborne.

"This will be a prolonged incident, with crews remaining on scene throughout the night," he added.

"As we head into the morning, disruption is expected to increase, and we urge people to avoid the area wherever possible." (BBC)