Oleksiy Reznikov told parliament that Russia has surrounded Ukraine with 149,000 troops and that more forces appeared to be on their way.

But he stressed that Ukraine would refrain from giving Russia any reason to attack its western neighbour.

"Ukraine is stepping up its defences. But we have no intention of conducting military operations against (eastern separatists) or Crimea," Reznikov said.

"Our mission is not to do any of the things the Russians are trying to provoke us into doing."

"We have to push back but keep a cool head," he said as fears mount that Russia may use an escalation in fighting as a pretext for launching an all-out invasion of Ukraine.