European Parliament President Roberta Metsola called for the “immediate adoption of a new package of forceful sanctions” against Russia on Monday, claiming that Moscow’s choice to invade Ukraine would be “the costliest mistake that the Kremlin has ever made.”

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Metsola told the European Parliament in Strasbourg, France, that any economic measures imposed on Russia “must be proportionate to the unprecedented atrocities that we are seeing,” adding that any additional penalties must “target those who bankroll and support Putin and close any existing loopholes.”

“These coordinated acts of inhumanity cannot remain unanswered, and we will hold all those responsible to account,” she added.

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Metsola told European parliamentarians that “atrocities committed by the Russian army in Ukraine are horrific. They are disgraceful, and they are shameful.”

Images of mass graves and killed civilians  “are war crimes, that are perpetrated by war criminals,” according to the Maltese lawmaker.

Mestola, who visited Ukraine last week and addressed the Ukrainian Parliament, told European legislators that she “was proud to take our message to Kyiv and to show that our parliament stands with them in these dark times.”

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“Ukraine is fighting for our values, in the most impossible conditions, and we have to support them,” she said. 

Following Metsola’s words, European parliamentarians observed a minute’s silence in memory of the victims of Bucha and Irpin, as well as all those who have died in Ukraine’s conflict.

The places in Ukraine where mass graves and murdered civilians were discovered “have been under the occupation, under the control of the aggressor, of the Russian troops, or they have been bombed out by the aggressor, the Russian troops,” said Peter Stano, European Commission spokesperson for international affairs, earlier on Monday.

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“There is no one else who could have committed these atrocities,” he added. 

Russia has denied any role in the killings, claiming that it does not target civilians and that photographs of victims on Bucha’s streets are fabricated.

Stano told reporters in Brussels that “the perpetrators of all these violations and war crimes will be held accountable,” adding that “government officials and military leaders will be held accountable.”