Relatives of passengers who were believed to have been killed in a plane crash react near the town of Semirom, Iran, February 18, 2017. (TASNIM PHOTO)

MOSCOW, Feb. 18 (Xinhua) -- Russian President Vladimir Putin has sent a message of condolences to his Iranian counterpart, Hassan Rouhani, over the crash of an Iranian jet, the Kremlin said Sunday.

An Iranian passenger plane crashed into the Dena mountain in central Iran's Isfahan province on Sunday morning, killing all the 66 people on board, the Civil Aviation Organization of Iran confirmed.

"The president emphasized that Russia grieves together with those who lost families and friends in the tragedy and wished them courage and strength in this dark hour," the Kremlin press service cited Putin as saying.