KYIV, April 27 - United Nations Secretary-General António Guterres, while on a visit to Kyiv on Thursday, said the U.N. would continue to push for a full-scale cease-fire as Ukraine fights off Russian invasion since February 24.

Guterres met with President Volodymyr Zelensky on Thursday after meeting with Russian President Vladimir Putin and Russian Foreign Minister Sergei Lavrov in Moscow earlier this week, The Wall Street Journal reported.

Guterres also visited Bucha, a commuter town just north of Kyiv where hundreds of residents were killed during Russia’s initial attempt to seize the Ukrainian capital in the early days of the invasion and a subsequent occupation. The area is now the focus of a war-crimes investigation by the International Criminal Court, though Russia isn’t a party to the court and is unlikely to extradite any commanders to stand trial.

“I appeal to the Russian Federation to accept to cooperate with the International Criminal Court,” Guterres said. “But when we talk about war crimes, we cannot forget that the worst of crimes is war itself.”

Ukrainian authorities on Thursday filed criminal charges against 10 Russian soldiers accused of taking civilians hostage and mistreating them in Bucha, in the first such move by prosecutors investigating possible war crimes.

All were noncommissioned officers and privates from Russia’s 64th Separate Guards Motor Rifle Brigade, one of the units that took part in the monthlong occupation of the Kyiv suburb. Ukrainian authorities said they discovered more than 400 dead civilians after Russian forces retreated in late March, their bodies packed in mass graves or left splayed on streets and sidewalks.

Russia has previously rejected allegations of war crimes, including accusations of targeting civilians. (wsj/ez)