Airlines are avoiding Iranian and Lebanese airspace and cancelling flights to Israel and Lebanon, as concerns grow over a possible conflict in the region after the killing of senior members of militant groups Hamas and Hezbollah this week.

Singapore Airlines stopped flying through Iranian airspace from early Friday morning and is using alternative routes, saying safety is its top priority, it told Reuters in a statement.

Taiwan's EVA Air and China Airlines also appeared to be avoiding Iran airspace for flights to Amsterdam on Friday which previously had flown over Iran, Flightradar24 data showed.

The airlines did not immediately respond to a request for comment on the route changes.

In a bulletin, OPSGROUP, a membership-based organisation that shares flight risk information, advised traffic between Asia and Europe to avoid Iranian and Iraqi airspace, a day after sources told Reuters that top Iranian officials will meet the representatives of Iran's regional allies from Lebanon, Iraq and Yemen to discuss potential retaliation against Israel.

Many airlines, including U.S. and European airlines, already avoid flying over Iran, especially since the reciprocal missile and drone attacks in April between Iran and Israel.

Singapore Airlines' flight to London Heathrow early on Friday went north of Iran through Turkmenistan and Azerbaijan, rather than crossing through Iran as it did the day before, Flightradar24 showed.

However, a significant number of airlines on Friday were still flying over Iran, including United Arab Emirates carriers Etihad, Emirates and FlyDubai, as well as Qatar Airways and Turkish Airlines.

Over the past two days, Air India, Germany's Lufthansa Group, U.S. carriers United Airlines and Delta Air, and Italy's ITA Airways said they had suspended flights to Tel Aviv.

Airlines this week have also been cancelling and delaying flights to the Lebanese capital Beirut after a strike in the Israeli-occupied Golan Heights on Saturday. Israel has blamed the attack on Lebanon-based armed group Hezbollah, which denied involvement.

Canada on Thursday issued a notice to Canadian aircraft to avoid Lebanese airspace for one month due to the risk to aviation from military activity.

Britain has for the past month advised pilots of potential risk from anti-aircraft weaponry and military activity in Lebanon's airspace.

Should an all-out war break out in the Middle East, OpsGroup said civil aviation will likely face the risk of drones and missiles crossing airways, as well as the increased risk of GPS spoofing - a growing phenomena around Lebanon and Israel where militaries and other actors broadcast signals that trick a plane's GPS system into thinking it is somewhere it is not.

(Writing by Lisa Barrington; editing by Miral Fahmy and Ros Russell)