Ukrainian President Volodymyr Zelensky has called for Bucha to become a "symbol of justice" on the one-year anniversary of Russia's withdrawal from the town now synonymous with war crimes allegations.
"We must do everything to make Bucha a symbol of justice... We want every Russian murderer, executioner, terrorist to be held responsible for every crime," Mr Zelensky said, adding that "what happened in Bucha, the Russian army does it wherever it goes."
Earlier the Ukrainian president visited Bucha with leaders of Croatia, Moldova, Slovakia and Slovenia for a commemoration ceremony.
"What happened in Bucha, the Russian army does it wherever it goes," Zelensky said back in Kyiv.
He said the Bucha tragedy exemplified the "systemic genocidal violence, which is the essence of Russian actions in all Ukrainian occupied territories".
Ukraine estimates that around 1,400 civilians died around Bucha, and 637 in the town itself.
Ukraine will use its national judicial system to hold accountable "the majority of Russian murderers and terrorists," Mr Zelensky said.
It will also rely on the International Criminal Court "which is able to prosecute Russian war criminals of various levels within its jurisdiction".
Kyiv is also working on the establishment of a special tribunal for the crime of aggression.
In a video message this evening US Secretary of State Antony Blinken said the United States "will continue pushing for accountability and for justice for as long as it takes".
French President Emmanuel Macron has accused Moscow of having "allowed, even encouraged" war crimes in Ukraine.
"Russian agression has led to systematic war crimes against Ukraine and its population," he said in a video message played at the Kyiv meeting.
"And far from sanctioning these crimes which go against all the laws of war, Russia's leaders allowed them to happen, even encouraged them, in defiance of international law and with the clear objective of subjugating the Ukrainian nation through violence," said Mr Macron.
Meanwhile, the International Monetary Fund's board has approved a $15.6 billion support package for Ukraine to assist with the country's economic recovery.
The new four-year Extended Fund Facility "aims to anchor policies that sustain fiscal, external, price and financial stability and support economic recovery, while enhancing governance and strengthening institutions to promote long-term growth in the context of post-war reconstruction and Ukraine's path to EU accession," the Fund said in a statement.
Read full coverage of Russia's invasion of Ukraine
In the weeks following Russia's withdrawal from other towns near Kyiv, hundreds more bodies were found in homes, basements and shallow graves across the north.
Ukraine wants to establish a special tribunal to prosecute Russia's leaders but there are complex legal disputes over how it could work.
The International Criminal Court earlier this month issued an arrest warrant for Putin over the unlawful deportation of children from Ukraine.
Chief ICC Prosecutor Karim Khan has described Ukraine as a "crime scene".
Russia has repeatedly denied any abuses by its forces, and foreign ministry spokeswoman Maria Zakharova this week described scenes in Bucha as a "crude and cynical provocation" by Kyiv.
