LONDON/CHICAGO: Britain and Egypt asked their airlines on Wednesday to avoid Iranian and Lebanese airspace amid growing fears of a possible broader conflict in the region after the killing of senior members of militant groups Hamas and Hezbollah.

Britain's advisory to its airlines to avoid Lebanon's airspace came hours after Egypt instructed all of its airlines to avoid Iran's airspace for three hours in the early morning on Thursday.

Many airlines globally are revising their schedules to avoid Iranian and Lebanese airspace while also calling off flights to Israel and Lebanon.

Flights through conflict zones became a prominent industry safety issue a decade ago after Malaysia Airlines flight MH17 was shot down over Ukraine, killing all 298 people on board.

U.S.-based United Airlines said on Wednesday its flights to Tel Aviv, which were paused on July 31 due to security concerns, remained suspended. "We continue to closely monitor the situation and will focus on the safety of our customers and crews as we decide when to resume service," the airline said.

Its rival Delta Air Lines has paused its flights between New York and Tel Aviv through Aug. 31.

British carriers are not flying to Lebanon currently, according to flight tracking website Flightradar24.

Singapore Airlines stopped flying through Iranian airspace last Friday and is using alternative routes, saying safety is its top priority.

Similarly, Egyptian airlines have already been avoiding Iran's airspace. The new directive applies to all Egyptian carriers, including charter operators and other smaller airlines, said Mark Zee, founder of OPSGROUP - a membership-based organization that shares flight-risk information.

Egypt's NOTAM, a safety notice provided to pilots, said the instruction would be in effect from 0100 to 0400 GMT on Thursday.

"All Egyptian carriers shall avoid overflying Tehran (Flight Information Region). No flight plan will be accepted overflying such territory," the notice said, referring to the three-hour period specified.

Egypt's civil aviation ministry later confirmed on Wednesday the notice was intended to reduce flight safety risks in light of a notification it received from Iranian authorities.

"Military exercises will be conducted over Iranian airspace on Aug. 7 from 11:30 to 14:30 and from 4:30 to 7:30 on Aug. 8 Tehran time," the statement said.

The ministry's press statement followed an unnamed source quoted by the state-affiliated Al Qahera News TV as saying that Iranian authorities had said to avoid flying in the country's airspace because of "military exercises."

Iran's Acting Foreign Minister Ali Bagheri Kani spoke with the Egyptian foreign minister by phone on Wednesday, according to Iranian foreign ministry's website.

In 2020, Iranian air defence units said they mistakenly shot down Ukrainian International Airlines flight PS752, killing all 176 people on board, shortly after it took off from Tehran airport. At the time, they were on heightened alert because of increased tensions with the United States.

On Sunday, Jordanian authorities asked all airlines landing at its airports to carry 45 minutes' worth of extra fuel.

Countries in the region, including Jordan, closed their airspace earlier this year amidst aerial attacks on Israel. (Reporting by Joanna Plucinska in London and Rajesh Kumar Singh in Chicago; Additional reporting by Jaidaa Taha, Yomna Ehab and Mohamed Ezz in Cairo; Editing by Matthew Lewis, Rod Nickel, Marguerita Choy and Jamie Freed)