Ukraine's Volodymyr Zelensky said the situation on the front lines in the east of the country was getting tougher, with Russia throwing more and more troops into battle, hours after the two sides agreed to exchange dozens of prisoners of war. Earlier on Saturday, Ukrainian officials said a serious accident at a high-voltage substation had caused widespread power outages in and around the southern port city of Odesa, leaving half a million people without power. Follow our live blog to see how the day's events unfolded. All times are Paris time (GMT+1).
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