Airlines are largely avoiding Iranian airspace in their flights over the Middle East, according to flight tracker FlightRadar24, lengthening flight times and hiking up fuel costs as worries over a retaliatory attack from Israel targeting Iran grow.

Turmoil in the Middle East in the last year has led to confusion and upheaval for aviation, prompting airlines to frequently change routes as they reassess the safety of the airspace in the region.

"Most airlines have rerouted flights away from Iran, with the northern route taking flights through Azerbaijan, Turkmenistan, Afghanistan, Pakistan and India on their way to Asia, and the southern route flying over Egypt and Saudi Arabia," said FlightRadar24 spokesperson Ian Petchenik.

Some airlines have said they have resumed most of their operations across the Middle East since Iran hit Israel with a ballistic missile attack on Tuesday, leading to flight cancellations and delays.

Petchenik said most strategic changes to flights to avoid parts of the Middle East have been lifted in direct connection with the Tuesday attack.

Late on Wednesday, German group Lufthansa said it would resume flights to Erbil in Iraqi Kurdistan using a limited amount of Iraqi airspace, and will resume using Jordanian airspace on Thursday.

It added that flights to Tel Aviv, Beirut and Tehran will remain suspended for the time being.

(Reporting by Joanna Plucinska; Editing by Jan Harvey)