A mass grave said to contain hundreds of bodies has been discovered near the recently recaptured northeastern Ukrainian town of Izium.

Referencing the find in his nightly address, President Volodymyr Zelensky said Russia is leaving death behind it everywhere and must be held responsible.

“The necessary procedural actions have already started there, more information – clear and verified – should be available tomorrow,” he said.

Thousands of Russian troops fled Izium last weekend after occupying the city as a logistics hub.

The Kharkiv region’s chief police investigator told Sky News it is one of the largest burial sites in a big liberated town, with 440 bodies buried in one place.”

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“Some died because of artillery fire … some died because of air strikes.”

An Associated Press journalist saw the site in a forest outside Izium.

Amid the trees were hundreds of graves with simple wooden crosses, most of them marked only with numbers.

A larger grave bore a marker saying it contained the bodies of 17 Ukrainian soldiers.

At a summit in Uzbekistan, Russian President Vladimir Putin has praised China’s “balanced position” on the Ukraine war, while acknowledging Beijing has “questions and concerns” over the invasion.

He promised to explain Russia’s position to Chinese President Xi Jinping at the meeting, which has the two leaders together for first time since the war began.

Meanwhile, Pope Francis has spoken of the legitimacy of nations supplying weapons to Ukraine to help the country defend itself.

“This is a political decision which it can be moral, morally acceptable, if it is done under conditions of morality,” he said.