“We have significant troop losses. “It’s a huge tragedy for us,” Kremlin spokesman Dmitry Peshkov told Sky News on Thursday amid a steady push from Ukraine. Although Moscow declined to give an exact number, Ukrainian authorities said at least 18,900 Russian soldiers had been killed in the fighting since the invasion began on February 24. Moscow’s unprovoked aggression has led to more than four million people fleeing the country, killing or injuring thousands. Vadim Boichenko, the mayor of Mariupol, in the southern port, said on Wednesday that more than 5,000 civilians, including 210 children, had been killed there. In Bucha, near the capital Kyiv, Ukraine said there could be between 150 and 300 in a mass grave in a church where Putin’s troops are said to be slaughtering people. Russia has been charged with war crimes in connection with Bucharest’s assassination and has been subject to new sanctions from the West, including Putin’s daughters. This map shows the extent of the Russian invasion of Ukraine on April 6 (Press Association Pictures) Rejecting suggestions that the Russian president would appear in a war crimes tribunal, Mr Peshkov said: “We do not see any possibility of such a thing, we do not consider it realistic.” In the aftermath of the Bucharest assassinations, the UN General Assembly suspended Russia from the UN Human Rights Council, expressing “grave concern about the ongoing human rights crisis and the humanitarian crisis.” Russia reacted by leaving the council. Moscow had earlier denied that it had targeted civilians, saying the images of corpses in Bucha were “monstrous forgery” to justify further sanctions and to derail peace talks. “Ukraine has very successful experience in investigating the actual war crimes of some of the Ukrainian troops after the initial stage of the war in 2014-2015. These crimes were investigated. “These people were taken to court and convicted,” Peshkov said in a counterattack in Ukraine. The war-torn nation has called on allies to stop buying Russian oil and gas amid divisions in Europe and to strengthen it militarily. In a speech to the nation on Thursday, Ukrainian President Volodymyr Zelensky said: “Ukraine needs weapons that will give it the means to win on the battlefield and this will be the strongest possible sanction against Russia.” He said the situation in Borodyanka, about 15 miles from Bucha, was “significantly worse”. UN humanitarian chief Martin Griffiths said on Thursday he was not optimistic about securing a ceasefire to end the fighting, as Russia turned its attention to the eastern Donbas region. “I think it will not be easy because the two sides, as I know now … have very little trust in each other. “I am not optimistic,” he said. The Independent has a proud campaign history for the rights of the most vulnerable and we first launched our “Welcome Refugees” campaign during the war in Syria in 2015. Now, as we renew our campaign and start this report on In the wake of the unfolding Ukrainian crisis, we call on the government to move faster and faster to secure aid. To learn more about our Refugee Campaign, click here. To sign the application click here. If you would like to donate, click here for our GoFundMe page.