LONDON: Flights at Britain's Heathrow resumed late on Friday (Mar 21) after a fire knocked out its power supply and shut Europe's busiest airport for the day, stranding tens of thousands of passengers and causing travel turmoil worldwide.

Heathrow said its teams worked tirelessly to reopen the world's fifth busiest airport after it was forced to close entirely after a huge fire engulfed a nearby substation on Thursday night, with travellers told to stay away.

The airport had been due to handle 1351 flights on Friday, flying up to 291 000 passengers, but planes were diverted to other airports in Britain and across Europe, while many long-haul flights returned to their point of departure.

Heathrow said there would be a limited number of flights on Friday, mostly focused on relocating aircraft and bringing planes into London.

"Tomorrow morning, we expect to be back in full operation, to 100 percent operation as a normal day," said Heathrow chief executive Thomas Woldbye. "What I'd like to do is to apologise to the many people who have had their travel affected ... we are very sorry about all the inconvenience."

Police said that after an initial assessment they were not treating the incident as suspicious, although enquiries remained ongoing. London Fire Bri...