Ukrainian security forces killed about 20 pro-Russian rebels who tried to seize control of police headquarters in the eastern port city of Mariupol on Friday, the Interior Minister said.
Minister Arsen Avakov said the attempt by "terrorists" to storm the building in a key industrial and shipping centre turned into a pitched battle within its walls. Some rebels had fled and were seeking shelter in the town.
Sanctions:
European Commissioner Janusz Lewandowski said he expects the European Union on Monday to strengthen its targeted sanctions against individuals and entities linked to Russia's intervention in Ukraine.
"In my opinion on Monday the latest strengthening of personal sanctions will come into effect," Lewandowski said in an interview with Polish broadcaster TVN 24 BiS.
"Those are not the most painful; the third level of sanctions is reserved in case a Russian intervention in Ukraine is proven beyond doubt."
Reactions:
The European Union criticized Russian President Vladimir Putin for attending a military parade in Crimea on Friday, saying he should not use the commemoration of victory in World War Two to showcase Russia's annexation of the region.
"The European Union notes with regret the presence of President Vladimir Putin at a military parade ... in Sebastopol, Crimea," Maja Kocijancic, spokeswoman for EU foreign policy chief Catherine Ashton, said.
"An important day in our shared history, dedicated to honoring the enormous sacrifices and giving remembrance to the millions of dead in the Second World War, should not have been instrumentalised to give visibility to the illegal annexation of Crimea," she said.
In turn, Ukraine's Foreign Ministry condemned a visit by President Vladimir Putin to the Crimean peninsula annexed by Russia in March as a deliberate escalation of a crisis between the two countries.
"Such a provocation is yet another confirmation that Russia is deliberately pursuing further escalation of tensions in Ukrainian-Russian relations," Ukraine's Foreign Ministry said in a statement.
This as Russian President Vladimir Putin, speaking in the Crimea region Russia annexed from Ukraine, said Russians' rights, including the right to self-determination, should be treated with respect.
"We treat all countries, all peoples, with respect. We respect their lawful rights and interests. But we ask that everybody should treat our lawful interests, including restoring historical justice and the right to self-determination, in the same way," he told a crowd at a concert during his first visit to Crimea since its annexation in March.
For his part, Polish Prime Minister Donald Tusk said that President Vladimir Putin's call on separatists in Ukraine to postpone a planned referendum has had no practical effect.
"As things stand today it seems to me that President Putin's words had no practical dimension whatsoever," Tusk told a news conference.
This as, France attacked calls by separatists for self-rule referendums in Ukraine.
"France in particular condemns the decision by separatists in eastern Ukraine to hold illegal referendums," Foreign Minister Laurent Fabius said in a statement. "The immediate priority is de-escalation, commitment to national dialogue and preparation of May 25 elections."
REUTERS