The situation in Nagorno-Karabakh region causes serious concern, the sides should evade further escalation of the conflict, Collective Security Treaty Organization (CSTO) Secretary General Nikolai Bordyuzha said Sunday, reports.

“We are greatly concerned about the situation in the Caucasus, especially in connection with the Karabakh conflict, where on the contact line heavy weapons, tanks are used, there are casualties,” Bordyuzha said in an interview to Rossiya-24 television.

He added that political resource of the CSTO states should be used to prevent further destabilization of the situation.

“To ensure that this conflict, that is already in a fairly hot stage, does not turn into a large-scale military clashes,” Bordyuzha stressed.