Updated

Georgia's attack on its breakaway South Ossetia region marked the start of last year's war with Russia, which retaliated with excessive force, an EU-commissioned report said Wednesday.

The report on the five-day war in August 2008 lay blame on both sides, but cited Georgia as starting the conflict with its night shelling in South Ossetia — an act it said was not justifiable under international law.

The EU report went on to blame Russia for conducting a military campaign deep inside Georgia. "All this cannot be regarded as even remotely commensurate with the threat to Russian peacekeepers in South Ossetia," the report said.

Russia's retaliation went "far beyond the reasonable limits of defense," it said, criticizing the devastating Russian assault on a tiny neighbor that in recent years has moved closer into the West with hopes of joining NATO.

In a first reaction, Georgia's EU Ambassador Salome Samadashvili said the question of who fired first on Aug. 7, 2008, was immaterial without considering two decades of friction.

She said the "report gives the full context," referring to Russia's invasion of Georgia's separatist regions of Abkhazia and South Ossetia.

Russia's EU envoy Vladimir Chizhov said it was "not a pro-Russian report, (but) it provides an unequivocal answer to the main question of 'Who started the war?"'

Georgia's assault on the South Ossetian capital of Tshkinvali "marked the beginning of large scale hostilities," Chizhov said. "Of course, this had been preceded ... by a lengthy period of growing tensions and provocations."

The report, written by Swiss diplomat Heidi Tagliavini, also addressed claims of ethnic cleansing of Georgians living in South Ossetia, but did not pinpoint who it thought responsible.

"There was evidence of systematic looting and destruction of ethnic Georgians villages in South Ossetia. Consequently, several elements suggest the conclusion that ethnic cleansing was indeed practiced," the report said.

Western capitals have generally tended to see Russia as the aggressor. EU countries said in a statement they hoped the report "can contribute toward a better understanding of the origins and the course of last year's conflict."

Chizhov said the report should encourage a rethink among "those leaders who have been hesitant" to blame Georgia for the war.

He rejected the notion that Russia responded with disproportionate use of force. "Russia's reaction was quite proportional, swift and to the point," he said.

The war ended with Russian forces decimating Georgia's military and driving its troops out of South Ossetia and Abkhazia, which Russia has since recognized as independent states. Russia keeps thousands of troops in the regions, from which it has blocked EU monitors.

Blaming Georgia is seen as boosting Russia's effort to get international recognition for the regions — only Nicaragua and Venezuela have followed suit.

It also could undermine Georgia's hopes of soon becoming a NATO member.

Putting the onus on Russia, however, could reinforce Russia's belief that the West is biased against it.

The report is based on research by 30 European military, legal and history experts.

The EU mandated the report last year to investigate the "causes and roots" of the conflict, but not to determine guilt so it could be used for compensation claims.