The United Nations on Tuesday said there was a "high likelihood" that the children's hospital in Kyiv suffered "a direct hit" from a Russian missile.Danielle Bell, head of the UN Human Rights Monitoring Mission in Ukraine, called Monday's strike "one of the most egregious attacks that we've seen since the onset of the full-scale invasion" in February 2022.She was speaking after Russia attacked cities across Ukraine on Monday with a missile barrage that killed more than three dozen people and ripped open the Okhmatdyt children's hospital in Kyiv, sparking international outcry.Dozens of volunteers including hospital staff and rescue workers dug through debris from the hospital in a desperate search for survivors after the rare daytime bombardment, AFP journalists on the scene saw.Russia has denied that it was responsible for the hospital strike, claiming the extensive missile damage in Kyiv was caused by Ukrainian air defense systems.But Bell told reporters in Geneva that video footage "shows the weapon directly impacting the hospital."The Okhmatdyt pediatric hospital is a children's specialist facility where families from across the country bring their children for treatment of serious medical conditions, such as cancer and kidney disease, she said, speaking via video link from Kyiv."Analysis of the video footage and assessment made at the incident site indicates a high likelihood that the children's hospital suffered a direct hit, rather than receiving damages due to an intercepted weapons system."This must be investigated," said Bell, who said her team and military experts had observed the damage at the hospital and spoken to staff, patients' parents and local residents.She said that at the time of the attack, 670 child patients and more than a thousand medical staff were present.Bell said Russia had likely fired from an aircraft a Kh-101 air-to-surface cruise missile armed with several hundred kilograms of explosives."The factors suggesting that it was a direct hit are based on video footage which shows the technical specification of the type of weapon that was used; it shows the weapon directly impacting the hospital, rather than being intercepted in the air," said Bell.