Abu Dhabi-based Etihad Airways and Bahrain's Gulf Air announced their decisions after a similar move by Dubai-based Emirates, the Middle East's largest carrier.
The Obama administration yesterday ordered US airlines not to fly over Iraq following US airstrikes launched against the Islamic State extremist group, which has seized much of northern and western Iraq.
Etihad said the decision was taken to avoid "conflict airspace," while Gulf Air said it would re-route flights to Europe using "alternate, more secure flight paths" to avoid northern Iraq.
Gulf Air said it is reviewing its Iraq operations on a daily basis but that flights to the country continue as normal for now.
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It added that it is "working closely with government and air traffic control authorities in Iraq to prepare for all eventualities."
Gulf Air runs three weekly flights to Baghdad and daily flights to Najaf, a key Shiite holy city and pilgrimage centre.
Turkish Airlines today said it was changing its flight times to Irbil. The decisions come three weeks after a Malaysia Airlines plane with nearly 300 people on board was shot down over eastern Ukraine.
US cargo planes have also begun airlifting aid to civilians stranded in the mountains of northern Iraq after fleeing from the Islamic State group.