Russia backed Sokhumi’s version of events and said Abkhaz forces were attacked by “a Georgian squad of saboteurs” on September 20.

“The attack,” the Russian Foreign Ministry said in a statement on September 21, “was carried out on the Abkhaz Interior Ministry’s anti-terrorist unit's base close to Tkvarcheli.”

It said that “a serious armed clash in a hotspot is a source of deep concern for the Russian Foreign Ministry.”

Two Abkhaz militiamen were killed, two injured and seven others captured after the clash on September 20, according to the Georgian Interior Ministry. The authorities in Sokhumi have alleged that the Georgian side also sustained casualties, but officials in Tbilisi have denied this.

The actual location of the clash remains a major point of contention.

Irakli Alasania, Georgia’s representative to the UN, said at a news conference in New York that the clash occurred at the foot of Khojali mountain, on the north-east slope. 

Significantly, Alasania's account places the scene of the clash on the Georgian side of the border, over 10 kilometers from Tkvarcheli. 

Apsnipress, the Abkhaz news agency, also said on September 21 that the clash occurred on Khojali mountain, but insisted it was in Abkhaz-controlled territory. "An [Abkhaz] observation post", it said, had been attacked, proving that the clash had occured within Abkhazia, and specifically in the Tkvarcheli district.

There has, however, been inconsistencies in Abkhaz reports about what was actually attacked.

The Abkhaz side initially said that a training camp had been attacked and conscripts killed. Then Abkhaz officials said a border guard training camp was the target. The Russian Foreign Ministry, however, said that an Abkhaz anti-terrorist unit’s base was attacked.

Georgian officials say that the clash occured in the vicinity of a strategic road which is currently under construction. The road will be a vital link between the Tbilisi-controlled areas in breakaway Abkhazia and Georgia proper.

Alasania said that an Abkhaz militia group, which had been intercepted several days ago by the road construction security team, aimed at “surveillance and demolition of the road and other infrastructure.”

He said the latest outburst was “part of a chain of alarming events” occurring since the Georgian central authorities had restored full control over upper Kodori Gorge last summer.

Tbilisi and Moscow have both called on the UN Observer Mission in Georgia (UNOMIG) to immediately investigate the incident.

The UN Secretary General’s spokesperson, Michele Montas, said on September 21 that UNOMIG was in the process of conducting an investigation.

A quadripartite Joint Fact-Finding Group (JFFG), in accordance with procedures, will be convened, which will be led by UN observers. The group will also include Russian peacekeepers, and representatives of both the Georgian and Abkhaz sides.

The conclusions and findings of the group will have to reflect the views of all four sides. Past experience has shown that such a consensus-based approach often leads to inconclusive reports. A similar investigation into the March 11 aerial attack on upper Kodori Gorge is a case in point.