UKRAINE/BELARUS BORDER, April 8 (Reuters) - More than 30 children were reunited with their families in Ukraine this weekend after a long operation to bring them back home from Russia or Russian-occupied Crimea, where they had been taken from areas occupied by Russian forces during the war. The three said they had been separated from their parents who were pressured by Russian authorities to send their children to Russian summer camps for what was billed as two weeks, from occupied parts of Kherson and Kharkiv regions. Kateryna Rashevska, a lawyer from a Ukrainian NGO called Regional Centre for Human Rights, told the briefing they were collecting evidence to build a case that Russian officials deliberately prevented return of the Ukrainian children