(Reuters) -Britain's Heathrow Airport said on Friday that it had begun reopening after a massive fire at a nearby electrical substation knocked out power, forcing a shutdown at Europe's busiest airport and disrupting the flight schedules of airlines globally.

At least 120 inbound flights to Heathrow were diverted to other airports, according to flight-tracking website FlightRadar24.

Here are the top 10 airlines by capacity whose aircraft were set to arrive at Heathrow Airport on Friday.

AIRLINE FLIGHTS SEATS

British Airways 341 67,962

Virgin Atlantic 31 9,058

Lufthansa 21 3,780

American Airlines 20 5,744

Aer Lingus 19 3,484

United Airlines 17 3,673

SAS 14 2,520

Swiss 12 2,000

Eurowings 13 1,906

Delta Air Lines 11 2,687

Other 67 airlines 143 9,790

Total 669 145,836

Here is what airlines are saying about the closure:

* British Airways: "We've been given clearance by HeathrowAirport to depart eight of our long-haul flights today from 7pm.We are now urgently contacting customers to let them know sothey can make their way to the airport from 5pm." * United Airlines: We will continue to adjust our flyingschedule to London in close coordination with airportauthorities. At this time, we expect to operate most scheduledFriday departures to London. * Air India: "London Heathrow-bound AI129 from Mumbai isreturning to Mumbai; AI161 from Delhi is diverting to Frankfurt.All our remaining flights to and from London Heathrow, includingAI111 of this morning, have been cancelled for 21 March." * Aer Lingus: "Cancelling all flights to and from LondonHeathrow Airport until further notice today following theclosure of the airport by the authorities." * Virgin Atlantic: "This has had a significant impact on ourflying programme both into and out of Heathrow and all VirginAtlantic arriving and departing flights are cancelled untilmidday on March 21, with the rest of today's schedule currentlyunder review." * Qantas: "Our Singapore-London and Perth-London serviceswere diverted to Paris today, with buses arranged to takecustomers on to London." * Scandinavian Airlines System: "All our 12 round trips areso far cancelled to and from Heathrow. We will keep affectedpassengers informed." * Ryanair: The airline said in a post on X that it had addedup to eight rescue flights between Dublin and London Stansted torescue passengers affected by Heathrow's closure. * Singapore Airlines: A spokesperson for the airline saidfour flights from Singapore to London were affected and fourflights from London to Singapore had been cancelled. * JetBlue: All JetBlue flights to and from Heathrow will becancelled and additional flights may be scheduled once theairport reopens to accommodate affected passengers. * Delta Air Lines: "Delta has suspended operations toHeathrow Airport and provided customers additional flexibilityin rebooking their travel." * American Airlines: "American issued a travel alert,providing additional flexibility for customers impacted by theLondon Heathrow Airport closure." * Emirates: The airline said it would resume flightoperations starting with flight EK07 from Dubai to London onMarch 22, following the reopening of Heathrow Airport.

Source: Data from Cirium Ascend, company statements.

Note: The seats represent capacity, not ticketed passengers.

(Reporting by Raechel Thankam Job, Abhijith Ganapavaram, Jamie Freed, Surbhi Misra, Angela Christy, Devika Nair, Aatreyee Dasgupta and Chandini Monnappa; Editing by Anil D'Silva and Pooja Desai)