Kiev - (AFP) - At least 23 people, including three children, were killed Thursday in raids on a city in central Ukraine, which President Volodymyr Zelensky described as a "flagrant act of terrorism".

The raids targeted an area hundreds of kilometers from the front lines, at a time when The Hague hosts a conference on crimes committed in Ukraine.

In a video intervention to the conference organized by the International Criminal Court, the European Commission and the Netherlands, Zelensky called for the establishment of a "special court" to investigate "the crimes of Russian aggression against Ukraine."

In Venice, photos released by the Ukrainian Emergency Service showed dozens of charred corpses and a ten-storey building destroyed by the explosion and ensuing fire.

The Ukrainian army indicated that "three missiles" targeted a parking lot and a commercial building in the city center that contains offices and small companies. Ukrainian Air Force spokesman Yuriy Ignat said that submarines in the Black Sea fired these missiles.

After the raids, Zelensky said in his intervention before the Hague Conference, in which European justice and foreign ministers are participating, "Every day, Russia kills civilians and kills Ukrainian children, and fires missiles at civilian targets where there is nothing military. What is this if it is not an outright terrorist act?"

And the rescue teams announced, in a new toll, that 23 people were killed, confirming that the search for 39 people is continuing.

The Secretary-General of the United Nations, Antonio Guterres, condemned the "horrific" attack, calling for accountability for those responsible for such attacks that affect civilians.

The European Union also condemned in "the strongest terms" the Russian strikes on Venice, according to a statement.
- Raids in the south -
For several weeks, Russian strikes away from the front lines of the front were relatively rare. But the war is expanding and raging around areas such as the strategic port of Mykolaiv in the south, close to the Black Sea, which was, early Thursday morning, the target of a "massive missile strike", for the second day in a row.

"Two schools, transportation infrastructure and a hotel were damaged," the Ukrainian presidency said in its daily morning briefing.
Pictures published by the local authorities showed the remains of a building destroyed by the bombing, while municipality workers were cleaning up the debris left by the attack.

Several weeks ago, Kiev launched a counterattack to recapture Kherson, located 60 kilometers from Mykolaiv and the only regional capital that Moscow has seized since February 24. While the front line remains relatively stable, Ukraine is mounting increasingly powerful attacks using new American and European missile systems targeting weapons depots.

- 'A complete victory' -
The main battles remain concentrated in eastern Ukraine and in the Donbass, the industrial and mining basin that Moscow vowed to completely occupy.
The governor of the Luhansk region, Sergey Gaidai, indicated that "artillery and mortar attacks continue (and) the Russians are trying to storm Seversk and open the way towards Bakhmut," where a civilian was killed in a bombing on Wednesday night.
The Moscow-backed separatists confirm that they are close to achieving a new victory, days after they took control of several important cities.
The Russian news agency "Tass" quoted the separatist official, Daniel Bezunov, as saying, "Servsk is now under our practical control, which means that we can target the enemy in the entire region."
AFP was not able to independently confirm this information.
A little further north, in the Izyum region, a soldier present in the dozens of meters long maze of trenches dug by the Ukrainian army told AFP, to the sound of artillery, "We dig when it's calm, we hide when the shooting starts."
However, one of the officers confirmed that "the situation is under control," noting that the Russian army is no longer advancing in this area, and that the goal is "complete victory."
Meanwhile, the authorities appointed by Moscow in the Ukrainian region of Zaporizhia, which is partially occupied by the Russian army, announced on Thursday their desire to organize a referendum on its annexation by Russia at the beginning of autumn.
"I made a decision to hold a referendum at the beginning of autumn," said Yevgeny Paletsky, head of the civil and military administration set up in this Russian-controlled area.

- 'Grain debates' -
Russia and Ukraine on Wednesday, during a meeting of military experts in Istanbul, made progress on the thorny issue of preventing grain exports from Ukrainian ports.
UN Secretary-General Antonio Guterres said that "already substantial progress" had been recorded, and he hoped to conclude a "formal agreement" soon. He spoke of "a glimmer of hope to alleviate human suffering and hunger in the world."
The agreement, which Guterres negotiated over a period of more than two months, aims to remove about 20 million tons of grain from Ukrainian silos across the Black Sea, mainly in Odessa, and to facilitate Russian exports of grain and fertilizer.
Ukraine is one of the world's major exporters of wheat and other grains. And the halt in exports heralds the continuation of the global rise in food prices, which threatens the risk of famine, especially in Africa.
US Treasury Secretary Janet Yellen said Thursday before the G20 meeting in Indonesia that the war in Ukraine is the "biggest challenge" to the global economy.
French President Emmanuel Macron also warned that the conflict in Ukraine "will continue" and that the French should be ready to dispense with Russian gas, which Moscow uses as a "weapon of war".
Andriy Yermak, director of the Ukrainian presidency, said that "the weapons supplied by the West are registered and sent to the front" but that a parliamentary oversight committee would make the process "as transparent as possible".