Tanks and shots heard in Ukrainian town of Mariupol
9 May 2014 Last updated at 12:25 BST
Several people are reported to have been killed in a shoot-out between Ukrainian troops and separatists in the town of Mariupol.
It came as Russia held a huge parade to mark 69 years since the Soviets defeated the Nazis.
President Vladimir Putin has flown to Crimea, which Russia annexed in March, amid celebrations of the Soviet victory over Nazi Germany in 1945.
The BBC's Regional Editor Olexiy Solohubenko reports.