Air Astana (KC, Astana Nursultan Nazarbayev) and Cathay Pacific (CX, Hong Kong International) have altered their flight paths over northern Iran around the Caspian Sea region following the Russian Navy's announcement that its Caspian fleet had begun launching surface-to-surface Kalibr-Nk guided missiles against Islamic State terrorists in Syria and Iraq.

The European Aviation Safety Agency warned airlines that there had been several launches of missiles from warships, located in the Caspian Sea, to Syria on October 6 and 7, 2015.

"Before reaching Syria, such missiles are necessarily crossing the airspace above Caspian Sea, Iran and Iraq, below flight routes which are used by commercial transport aeroplanes," it said urging airlines to use more northerly routes when crossing from Europe to Asia and vice versa.

Airlines have been wary of transiting active war zones following the downing of Malaysia Airlines (MH, Kuala Lumpur International) flight MH17 over eastern Ukraine last year by a missile.