According to Human Rights Watch, there is "evidence of war crimes committed in Bucha", the town northwest of Kiev for a long time occupied by the Russian armed forces.
The news is reported by the Wall street journal.
In detail, the human rights group claimed to have interviewed a woman who saw Russian troops round up five men and shoot one of them in the back of the head, killing him.
"We have documented a clear case of summary execution by the armed forces of the Russian Federation in Bucha on March 4," said a spokesperson for Human Rights Watch.
"The Bucha massacre was deliberate. The Russians aim to eliminate as many Ukrainians as possible. We must stop them and drive them out."
This was stated by Foreign Minister Dmytro Kuleba on twitter.
Kuleba calls for "new devastating G7 sanctions now: embargo on oil, gas and coal; close all ports to Russian ships and goods; disconnect all Russian banks from Swift".
The Kiev government had reported executions of civilians by Russian soldiers.
"Bucha, Kiev region. The bodies of people with their hands tied, shot dead by Russian soldiers, lie in the streets. These people were not in the army. They had no weapons. They posed no threat. How many. Are other similar cases happening right now in the occupied territories? ", writes the advisor to the Ukrainian president Mykhaylo Podolyak on Twitter, posting a photo of three dead bodies on the street, one of which has his arms tied behind his back.
The body of Oleksandr Sukhenko, a former footballer of the Seagull Second League club, was found in a mass grave near Motyzhyn, in the Bucha district.
This was reported by the Ukrainian agency UNIAN, stressing that he was killed along with his parents.
His mother Olga Sukhenko was the head of the village of Motyzhyn and his father Igor Sukhenko was the president of the local football team Kolos.
Witness reports from the newly liberated battered city of Bucha reveal
accusations against Russian soldiers who allegedly used Ukrainian children as "human shields"
on their vehicles to protect their movements.
The Guardian reports it.
Ukraine's Attorney General is collecting a dossier of allegations about the Russians' use of local children to avoid being targeted during their retreat from the Ukrainian capital and other parts of the country.
Witnesses told of strollers placed in front of tanks in the village of Novyi Bykiv, near the encircled city of Chernihiv, 100 miles north of Kiev.
It was also reported that the children were taken as hostages in a number of conflict hotspots across the country to ensure that locals did not provide the coordinates of the enemy's movements to Ukrainian forces.
"Cases of using children as a cover have been reported in the oblasts (ed. Regions) of Sumy, Kiev, Chernihiv and Zaporizhzhia," said Lyudmila Denisova, Ukrainian human rights ombudsman.
Colonel Oleksandr Motuzyanyk, a spokesman for the Ukrainian Defense Ministry, said the reported cases are being investigated by the country's Attorney General, but was unable to provide further details.
He said: "Enemies used Ukrainian children as human shields when moving their convoys. Russian soldiers used Ukrainian children as hostages, loading them onto their trucks to protect their vehicles while on the move."
Ukraine's Attorney General said at least 412 children have been injured or killed since the invasion began in February.