West warns Russia of 'consequences' ahead of referendum

France and Germany today warned Russia of "consequences" if Moscow continued to sow unrest ahead of Ukrainian elections later this month, on the eve of "illegal" referendums the West fears will split the country apart.

In a joint statement, French President Francois Hollande and German Chancellor Angela Merkel also urged Ukraine's security forces to stop their offencive on rebel-held positions ahead of the planned May 25 presidential election.

The warnings suggested the West might soon move to broaden its sanctions regime to include whole sections of the recession-bound Russian economy.

But the call for the pro-Western government in Kiev to row back its military action echoes a similar statement by Russian President Vladimir Putin on Wednesday, who set that as his condition for backing the election.

"If the internationally recognised presidential elections do not take place on May 25, this would destabilise the country further. France and Germany believe that in this case, appropriate consequences should be drawn," indicating stepped-up sanctions, the two leaders said.

Paris and Berlin said that "proportionate" force should be used to protect people and buildings as Kiev battles to wrest back control of more than a dozen towns and cities in eastern Ukraine held by pro-Russian insurgents.

However, they stressed that "the Ukrainian security services should refrain from offencive actions before the election".

Paris and Berlin also called for a "visible" withdrawal of Russian troops from the Ukrainian border. Putin said on Wednesday the estimated 40,000 servicemen had been pulled back but NATO said there was no sign of that.

Ukraine's interim president Oleksandr Turchynov said that Kiev was "ready for negotiations" with representatives from the region but "not terrorists whose mission is to destroy the country".

But the head of the separatists in the flashpoint eastern town of Slavyansk, Vyacheslav Ponomaryov, told reporters that "if the junta (the Ukrainian government) doesn't withdraw its troops, there will be no discussions".

While the diplomatic pressure on Russia intensified, the situation on the ground remained combustible as the southern city of Mariupol observed a day of mourning for up to 21 people killed in clashes on Friday between Ukrainian authorities and pro-Russian separatists.