The order was given on Friday after Georgian forces fired shells into South Ossetia’s main city Tskhinvali and its outlying villages for several hours overnight, a spokeswoman for the separatist government said.

"A general mobilisation has been declared … If the shelling resumes, South Ossetia will respond with heavy weaponry," Irina Gagloyeva said.

General Mamuka Kurashvili, a Georgian army officer, said the shelling came in response to an attack on a Georgian checkpoint by South Ossetian forces.

'Open aggression'

Russia said on Friday that Georgia's actions were an act of open aggression.

In a statement, the Russian foreign ministry said: "The actions of Tbilisi show that an open act of aggression has been committed against South Ossetia."

Russian news agencies also quoted the head of Russia's peacekeeping troops in South Ossetia as saying more soldiers could be deployed there if the tension worsens.

South Ossetia has not yet gained international recognition since it drove out Georgian government forces in 1992.

The rising tensions in South Ossetia come as Abkhazia, another breakaway region of Georgia, continues to assert its independence from Tblisi.

Both regions have formal ties with Russia, which contends that Georgia is preparing to take control of the separatist areas by force.

Tblisi accuses Moscow of trying to absorb both regions into Russia, in an attempt to thwart its attempts to join the Nato military alliance.

Russia’s foreign minister has called on Georgia not to use violence, according to a report by the Interfax news agency.

"We are seriously concerned by the latest events in South Ossetia,” Sergei Lavrov was quoted as saying, during a visit to Turkmenistan.

“We must persuade Tbilisi to sign a legally binding document guaranteeing non-aggression."

On Thursday, an explosion killed a police colonel in South Ossetia and authorities there said Georgia's secret services were behind the killing.

In a separate incident on Thursday, gunmen opened fire on Dmitry Sanakoyev, who is recognised by Georgia as South Ossetia's leader. He escaped the attack unhurt.


Agencies