(Updates with Ukraine defense ministry statement, Kyiv casualty figures, Kharkiv damage estimates) By Natalia Zinets and Natalie Thomas LVIV/ODESSA, Ukraine (Reuters) – Ukrainian President Volodymyr Zelenskiy called on Saturday for comprehensive peace talks with Moscow and also urged Switzerland to do more to crack down on Russian oligarchs who he said were helping wage war on his country with their money. British intelligence warned that Russia, frustrated by its failure to achieve its objectives since it launched the invasion on Feb. 24, was now pursuing a strategy of attrition that could in…