Two Russian journalists for a Russian state-owned TV channel died on Tuesday in eastern Ukraine after being hit by mortar fire, the Rossiya 24 network said.

Correspondent Igor Kornelyuk, 37, died during surgery in a hospital after being wounded while on assignment in Luhansk. The whereabouts of the sound engineer who was with him were unknown throughout the day, but in late evening the network announced that Anton Voloshin had been confirmed dead as well.

Russian officials expressed indignation over the deaths. Russian Prime Minister Dmitry Medvedev said the Ukrainian government should be held responsible, while Russia's federal investigative agency announced the opening of a criminal case.

"The violence affecting journalists in Ukraine is reaching unprecedented levels," said Johann Bihr from the Paris-based media advocacy group Reporters Without Borders. "We again call on the belligerents to do whatever is necessary to protect journalists as required by international law."

AP