Pro-Russian rebels shot down a Ukrainian helicopter in fierce fighting near the eastern town of Slaviansk today, and Kiev drafted police special forces to the southwestern port city of Odessa to halt a feared westward spread of rebellion.
Ukraine said the Odessa force, based on "civil activists", would replace local police who had failed to tackle rebel actions at the weekend. Its dispatch was a clear signal from Kiev that, while tackling rebellion in the east, it would vigorously resist any sign of a slide to a broader civil war.
Odessa, with its ethnic mix from Russians to Ukrainians, Georgians to Tatars a cultural contrast to the pro-Russian east, was quiet on Monday. Ukrainian flags flew at half mast for funerals of some of the dozens killed in clashes on Friday.
But in the east, fighting intensified around the pro-Russian stronghold of Slaviansk, a city of 118,000, where rebel fighters ambushed Ukrainian forces early in the day.
The Interior Ministry said five Ukrainian paramilitary police were killed. Separatists said four of their number had also been killed.
Pro-Russian separatists ambushed Ukrainian forces earlier today, triggering heavy fighting on the outskirts of the rebel stronghold of Slaviansk, Ukrainian interior minister Arsen Avakov was quoted as saying.
Reporters said at least two separatist armoured personnel carriers and several rebels fled the area, where almost continuous gunfire had been heard since morning.
The gunfire seemed closer to Slaviansk, in eastern Ukraine, than a day earlier.
“In the morning, a squad in the anti-terrorist operation was hit by an ambush by terrorist groups. They are using heavy weapons,” Mr Avakov was quoted as saying by Interfax-Ukraine news agency near Slaviansk.
He said there were fatalities on the Ukrainian side but did give a figure.
Pro-Russian separatists have seized key buildings in several cities and towns in eastern Ukraine, where many people are Russian speakers, since the ouster of president Viktor Yanukovich by pro-Western leaders in Kiev in February.
Yesterday pro-Russian militants stormed a Ukrainian police station in Odessa and freed 30 fellow activists as the prime minister blamed police corruption there for dozens of deaths in rioting on Friday.
"Russians won't abandon their own!" militants chanted as they smashed windows and broke down the gate at the compound, where comrades had been held since Friday's mayhem. Others shouted "Russia! Russia!" and "we will not forgive!"
Odessa police said 30 activists had been released. Some police officers were offered the black and orange St George’s ribbon, a Russian military insignia that has become a symbol of the revolt, and were cheered when they accepted it.
Questions have been raised about the ability of the army as well as police to confront an uprising Kiev claims is backed by Moscow and led in the field by Russian special forces - an accusation the Kremlin denies.
Police in the eastern port of Mariupol said yesterday pro-Russian rebels had tricked soldiers at a checkpoint into eating food laced with a sleeping potion.
The soldiers were then bundled off along with their weapons, prompting long talks to free them.