MOSCOW, June 18  -- The Moscow-led Collective Security Treaty Organization (CSTO), an intergovernmental military alliance, on Wednesday condemned Ukraine for continuing punitive operation in its southeastern regions and killings of Russian journalists.

"Killings of the Russian journalists once again revealed criminal essence of the forces, which have launched the punitive operation resulting in death of civilians," CSTO Secretary General Nikolai Bordyuzha said in a letter of condolences sent to the Russian VGTRK television company's chief.

"Authorities in Kiev and their foreign supporters are afraid of truth," the Interfax news agency quoted Bordyuzha as saying.

Two Russian journalists, Igor Kornelyuk and Anton Voloshin, who worked for the VGTRK, died Tuesday after being hit in mortar bomb reportedly fired by Ukrainian troops near Lugansk. The third reporter, Viktor Denisov, escaped unharmed.

Also on Tuesday, Russian President Vladimir Putin asked his Ukrainian counterpart Petro Poroshenko to ensure the safety of journalists in a conversation over the phone.

The deadly conflict in eastern Ukraine between insurgents and government troops has been raging for nearly two months. Reports of journalists being detained or kidnapped and refugees fleeing have aroused international concern.

The CSTO, which comprises Russia, Armenia, Kazakhstan, Kyrgyzstan, Tajikistan and Belarus, warned in May that no international military-political bloc should interfere into the Ukrainian crisis.