Ukraine crisis: Donetsk clashes over Odessa
4 May 2014 Last updated at 11:20 BST
Pro-Russian groups in Donetsk have been reacting angrily to the deaths in Odessa.
More than 40 people died there on Friday, most of them in a fire at the Trade Unions House, where separatist protesters had barricaded themselves following running battles with pro-Kiev activists.
Sarah Rainsford reports.