UNITED NATIONS (Reuters) -- Ukrainian President Volodymyr Zelenskyy told the United Nations Security Council that "accountability must be inevitable" for Russia as he accused Russian troops of committing "the most terrible war crimes" since World War Two.
Zelenskyy showed a short video of burned, bloodied and mutilated bodies, including children, in Irpin, Dymerka, Mariupol and Bucha.
Russia's U.N. Ambassador Vassily Nebenzia then told the Security Council that Russian troops are not targeting civilians, dismissing accusations of abuse as lies.
Zelenskyy questioned the value of the 15-member U.N. Security Council, which has been unable to take any action over Russia's Feb. 24 invasion of Ukraine because Moscow is a veto power, along with the United States, France, Britain and China.
"We are dealing with a state that turns its veto at the U.N. Security Council into the right to [cause] death," Zelenskyy said in a live video address from Ukraine's capital Kyiv, urging reform of the world body. "Russia wants to turn Ukraine into silent slaves."
Russia says it is carrying out a "special military operation" that aims to destroy Ukraine's military infrastructure and "denazify" it, and denies attacking civilians. Ukraine says it was invaded without provocation.
Russia's Nebenzia said Moscow was trying to bring peace to Ukraine's breakaway eastern Donbas region and was not trying to "conquer lands" in Ukraine.
"We are not shooting against the civilian targets in order to save as many as civilians possible. This is precisely why we're not advancing as fast as many expected," Nebenzia told the Security Council.
The U.S. ambassador to the United Nations, Linda Thomas-Greenfield, said responsible world powers and global leaders need to "show backbone -- and stand up to Russia's dangerous and unprovoked threat against Ukraine and the world."
"No one can be a shield for Russia's aggression," she said as Washington pushes to suspend Russia from the Geneva-based U.N. Human Rights Council. The 193-member U.N. General Assembly in New York is likely to vote on the move to suspend Russia on Thursday, diplomats said. A two-thirds majority is needed.
The United Nations said some 11 million Ukrainians -- more than a quarter of the population -- have fled their homes. More than 4 million of those people have left Ukraine.
U.N. aid chief Martin Griffiths said at least 1,430 civilians have been killed, including more than 121 children. "We know this is likely a serious underestimate," he added.
Griffiths, who is seeking a humanitarian truce in Ukraine, said "we have a long road ahead of us" after what he described as a "frank" meeting with Russia's Foreign Minister Sergei Lavrov in Moscow on Monday. Griffiths said he hopes to travel to Ukraine on Wednesday to meet with Ukrainian officials.
"Perilous conditions are hampering our efforts to access civilians - or for them to access us. Civilians must be allowed to move to safer areas without the fear of attacks," he told the Security Council.
U.N. political affairs chief Rosemary DiCarlo said the U.N. Human Rights Monitoring Mission in Ukraine was seeking to verify allegations of sexual violence by Russian forces.
"These include gang rape and rapes in front of children," she said. "There are also claims of sexual violence by Ukrainian forces and civil defense militias."
U.N. Secretary-General Antonio Guterres warned the Security Council that Russia's invasion of Ukraine is one of the greatest challenges ever to the international order "because of its nature, intensity, and consequences."
"This council is charged with maintaining peace - and doing so in solidarity," he said, voicing regret about the divisions that have prevented it from taking any action.
Thomas-Greenfield responded: "It is - and it is also the responsibility of U.N. leaders. And every member state with a voice in the GA (General Assembly)."