Heathrow Airport will be closed for all of Friday over a "significant" power outage linked to a fire at a nearby electrical substation that supplies it, BBC reported. 

The airport, which is the UK's busiest, has warned of "significant disruption" over the coming days and told passengers not to travel "under any circumstances" until it reopens.

"To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23:59 on 21 March 2025," a spokesperson said.

"We know this will be disappointing for passengers and we want to reassure that we are working as hard as possible to resolve the situation," they added, according to BBC.

"Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored," the Heathrow spokesperson said.

The airport has apologised for the disruption and has advised passengers to contact their airlines for further information.