Teimuraz Mamsurov, the head of Russia’s North Ossetian Republic, told Interfax news agency that “hundreds of volunteers are on their way to South Ossetia.”

“We are unable to stop them or to prevent them from going,” he added.

North Ossetia is linked with the breakaway region by a tunnel through Roki Pass.

The Georgian government said in a statement after midnight that “hundreds” of fighters and military hardware had entered breakaway South Ossetia from the Russian Federation via Roki Tunnel.

Meanwhile, Interfax news agency quoted an unnamed source from the Russian Foreign Ministry as saying that an emergency meeting of Russian diplomats was due to be convened. They will discuss the fighting in South Ossetia, the source said.