Lufthansa has resumed flights to Cairo after the German carrier joined British Airways in announcing a suspension.
Flights were cancelled on Saturday night, with the airlines issuing separate statements which cited security concerns.
BA said flights would be suspended for seven days while “further assessment” of security arrangements at Cairo airport took place.
Lufthansa said its own flights were suspended shortly after, citing “an unclear security situation”, but resumed service to the Egyptian capital on Sunday.
Passengers were informed on Twitter that services were resumed.
It remains unclear what prompted BA’s decision to halt flights.
BA said: “We constantly review our security arrangements at all our airports around the world and have suspended flights to Cairo for seven days as a precaution to allow for further assessment.
“The safety and security of our customers and crew is always our priority, and we would never operate an aircraft unless it was safe to do so."
ITV News Correspondent Ivor Bennett explains BA's decision to halt flights to Cairo
Customers who still wished to travel were offered a refund or the opportunity to be rebooked onto flights with alternative airlines.
It is understood British Airways made the Department for Transport aware of its decision ahead of the announcement.
BA operates one flight per day from Heathrow to Cairo.
Current Foreign and Commonwealth Office (FCO) advice on travel to Egypt warns against “all travel” to certain parts of the country.
But Cairo is part of a safer region, where the FCO only suggests reviewing its advice before visiting.
Current guidance also warns against “all but essential” travel by air to Sharm el Sheikh.
That advice followed the bombing of a Russian airline which was brought down in 2015 shortly after leaving the Red Sea resort, killing 224 people.