A Sukhoi Su-24 fighter jet takes off from the Hmeymim air base near Latakia, Syria, in this file handout photograph released by Russia's Defence Ministry October 22, 2015. [Photo/Agencies]

SEARCH FOR PILOTS

The Syrian Observatory for Human Rights monitoring group said the warplane crashed in a mountainous area in the northern countryside of Latakia province, where there had been aerial bombardment earlier and where pro-government forces have been battling insurgents on the ground.

Islamic State, which has beheaded foreign captives in the past, is not known to have a presence there.

One of the pilots was in the hands of Turkmen forces in Syria who were looking for the other one, broadcaster CNN Turk reported, citing local sources. Russian military helicopters were also searching for the pilots, Turkey's Dogan news agency reported.