Two former British military officers are expected to give crucial evidence against Georgia when an international inquiry is convened to establish who started the country’s bloody five-day war with Russia in August.

Ryan Grist, a former British Army captain, and Stephen Young, a former RAF wing commander, are said to have concluded that, before the Russian bombardment began, Georgian rockets and artillery were hitting civilian areas in the breakaway region of South Ossetia every 15 or 20 seconds.

Their accounts seem likely to undermine the American-backed claims of President Mikhail Saakashvili of Georgia that his little country was the innocent victim of Russian aggression and acted solely in self-defence.

During the war both Grist and Young were senior figures in the Organisation for Security and Cooperation in Europe (OSCE). The organisation had deployed teams of unarmed monitors to try to reduce tension over South Ossetia, which had split from Georgia in a separatist struggle in the early 1990s with Russia’s support.

On the night war broke out, Grist was the senior OSCE official in Georgia. He was in charge of unarmed monitors who became trapped by the fighting. Based on their observations, Grist briefed European Union diplomats in Tbilisi, the Georgian capital, with his assessment of the conflict.

Grist, who resigned from the OSCE shortly afterwards, has told The New York Times it was Georgia that launched the first military strikes against Tskhinvali, the South Ossetian capital.

“It was clear to me that the [Georgian] attack was completely indiscriminate and disproportionate to any, if indeed there had been any, provocation,” he said. “The attack was clearly, in my mind, an indiscriminate attack on the town, as a town.”

Last month Young gave a similar briefing to visiting military attachés, in which he reportedly supported the monitors’ assessment that there had been little or no shelling of Georgian villages on the night Saakashvili’s troops mounted an onslaught on Tskhinvali in which scores of civilians and Russian peacekeepers died.

“If there had been heavy shelling in areas that Georgia claimed were shelled, then our people would have heard it, and they didn’t,” Young reportedly said. “They heard only occasional small-arms fire.”

Bernard Kouchner, the French foreign minister who helped broker the ceasefire that ended the war and has been a fierce critic of the Russian invasion of Georgia, is tomorrow due to announce a commission of inquiry into the conflict at a meeting of EU foreign ministers in Brussels.

The inquiry will be chaired by a Swiss expert as a mark of independence and will try to establish who was to blame for the conflict. European and OSCE sources say it is likely to seek evidence from the two former British officers.

The inquiry comes as the EU softens its hardline position towards Russia amid mounting European scepticism about Saakashvili’s judgment.

Europe is preparing to resume negotiations with Moscow this month on a new partnership and cooperation agreement, which it froze when Russia invaded Georgia, routed its army and recognised the independence of South Ossetia and Abkhazia, another breakaway region.

Although Grist and Young know only part of the picture, their evidence appears to support Russia’s claim that the Georgian attack was well underway by the time their troops and armour crossed the border in a huge counter-strike.

Georgia attacked South Ossetia on the night of August 7-8. In the afternoon an OSCE patrol had seen Georgian artillery and Grad rocket launchers massing just outside the enclave. At 6pm the monitors were told of suspected Georgian shelling of a village.

Georgia declared a unilateral ceasefire. But at 11pm it announced that Georgian villages were being shelled and began a military operation to “restore constitutional order” in South Ossetia.

Soon afterwards the Georgian bombardment of Tskhinvali began. By 12.35am the OSCE monitors had recorded more than 100 rockets or shells exploding in Tskhinvali.

Russia sent in troops and armour, saying they were there to protect its peacekeepers and the civilian population. The invasion attracted worldwide condemnation and led to a deterioration in relations between Moscow and the West.

Many western leaders depicted Russia as an expansionist giant determined to crush its tiny neighbour. They rallied to Georgia’s defence amid calls for it to be rapidly admitted to Nato, Saakashvili’s most fervent wish.

The president argued that Russia had attacked Georgia because “we want to be free” and that his country was fighting a defensive war.

Critical to his argument was his claim that he had ordered the Georgian army to attack South Ossetia in self-defence after mobile telephone intercepts from the Russian border revealed that Russian army vehicles were entering Georgian territory through the Roki tunnel.

“We wanted to stop the Russian troops before they could reach Georgian villages,” Saakashvili said. “When our tanks moved toward Tskhinvali, the Russians bombed the city. They were the ones – not us – who reduced it to rubble.”

Russia counters that the war began at 11.30pm, when Saakashvili ordered an attack, well before any Russian combat troops and armour crossed the border through the tunnel.

HOW FIGHTING BROKE OUT

August 7, 3pm: OSCE monitors see build-up of Georgian artillery on roads to South Ossetia.

6.10pm: Russian peacekeepers inform OSCE of suspected Georgian artillery fire on Khetagurovo, a South Ossetian village.

7pm: Georgia declares a unilateral ceasefire.

11pm: Georgia announces that its villages are being shelled and launches attack in South Ossetia.

11.30pm: Georgian forces bombard Tskhinvali.

11.45pm: OSCE monitors report shells falling on Tskhinvali every 15-20 seconds.

August 8, 12.15am: Commander of Russian peacekeepers reports that his unit has taken casualties. Russia later announces that it has invaded Georgia to protect civilians and Russian peacekeepers.

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