ODESSA, May 5 - Ukraine's Interior Minister said on Monday he had drafted a new special forces unit into the southern port city of Odessa after the "outrageous" failure of police to tackle pro-Russian separatists in a weekend of violence that killed dozens, Reuters reported.

Fighting continued near the eastern city of Slavyansk where Ukrainian troops have been, somewhat tentatively, pressing a campaign to end pro-Russian rebellion. A Reuters correspondent said gunfire seemed to be coming closer to the city centre.

The violence in Odessa, a southwestern port with a broad ethnic mix from Russians and Ukrainians to Georgians and Tatars, is seen as something as a turning point in Kiev; a warning of dangers if rebellion spreads beyond the Russian-speaking east.

Interior Minister Arsen Avakov said the new Odessa force was based on "civil activists who wanted to help the Black Sea city "in these difficult days.” The entire leadership of the local police had been sacked and could face criminal action.

The Odessa violence was the deadliest since Moscow-oriented president Viktor Yanukovych fled to Russia in February and pro-Russian militants launched uprisings in the industrial east.

"The police in Odessa acted outrageously, possibly in a criminal fashion," Avakov said on his Facebook page. "The 'honor of the uniform' will offer no cover."

Ukrainian leaders have made it clear they see the police force across wide areas of the country as unreliable in the face of rebellion they say is backed by Moscow and led on the ground by Russian special forces. The units Avakov referred to emerged partly from the uprising against Yanukovych early this year.

That could fuel anger among the government's opponents, who accuse it of promoting "fascist" militant groups, such as Right Sector, which took part in the Kiev uprising over the winter.

Loss of control of Odessa would be a huge economic and political blow for Kiev, which accuses Moscow of scheming to dismember Ukraine.

Kiev's anger on Monday focused on the Odessa police decision to release 67 largely pro-Russian militants after supporters besieged and stormed a police station on Sunday.
The crowd of several hundred chanted "Odessa is a Russian city!" Russian is the first language of many of its residents.

The militants had been arrested on Friday after hours of clashes, with the use of petrol bombs and small arms, on the streets of the Black Sea city. Pro-Russian supporters withdrew to a building that later burnt down with the loss of over 40 people - bloodshed that Moscow blames on Kiev's "provocations".

The exact circumstances of the blaze remain unclear but the deaths have become a cause celebre for anti-Kiev activists across the south and east.

Avakov said other detainees had been transferred away from Odessa in the night to more central areas of Ukraine to prevent any premature release.

Russia denies ambitions to seize eastern Ukraine as it has annexed the Crimea peninsula but reserves the right to send troops to defend Russian-speakers if it deems necessary.

Separatists who have declared a "People's Republic of Donetsk" are planning a referendum on secession next Sunday.

The capital Kiev has remained quiet since the protests that forced Yanukovych to flee to Russia. But celebrations this week marking the anniversary of the Soviet victory in World War Two could be a source of tension. (rt/ez)