British Airways suspended flights to Cairo for a week to allow for a security assessment, the airline said on Saturday.
German giant Lufthansa quickly followed suit as it temporarily halted flights to the Egyptian capital from Frankfurt and Munich, but they appeared to resume a normal service on Sunday.
"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," a statement by BA said.
It added it would never operate an aircraft unless safe to do so.
A spokeswoman for the company declined to provide more information about why flights had been suspended and what security arrangements the airline was reviewing.
Three Egyptian airport security sources told Reuters that British staff were checking security at Cairo airport on Wednesday and Thursday.
The British Foreign Office advises against all but essential travel by air to and from the Egyptian resort of Sharm El Sheikh, where a Russian passenger jet was bombed in 2015, but has not issued similar warnings against air travel to and from Cairo.
The Foreign Office updated its travel advisory on Saturday to add a reference to the British Airways' suspension, advising travellers affected to contact the airline.
"There's a heightened risk of terrorism against aviation. Additional security measures are in place for flights departing from Egypt to the UK," the British advisory says.
The Egypt State Information Service could not immediately be reached for comment.
Egypt's Ministry of Civil Aviation said in a statement late on Saturday that it had contacted the British Embassy in Cairo which had confirmed that the decision to suspend the flights was not issued by Britain's transport or foreign ministries.
The Egyptian ministry added that it will add more flights from Cairo to London starting on Sunday "to facilitate transporting passengers during this period."
Tourism, a key source of foreign revenue for Egypt, has been recovering after tourist numbers dropped in the wake of a 2011 uprising and the 2015 bombing of the Russian jet, which killed all 224 people on board shortly after takeoff.
That attack, which was claimed by ISIS, prompted Russia to halt all flights to Egypt for several years and a number of countries, including Britain, to cease flights to Sharm El Sheikh, which have yet to resume.
