· High alert as four officers are held on spying charge
· Putin accuses leadership of act of state terrorism

Infuriated by the arrests of four Russian officers on spying charges, Moscow has put its troops in Georgia on high alert and ordered them to "shoot to kill" to defend their bases in the former Soviet republic.

In his first public comments on the escalating crisis, the Russian president, Vladimir Putin, yesterday accused Georgia of "state terrorism" and compared the arrests to the repressions of Stalin's secret police chief, Lavrenty Beria.

The commander of Russian military forces in Georgia, General Andrei Popov, said Russian law authorises the use of force to defend bases abroad from aggression. "We are ready to thwart any possible attempts to penetrate our facilities using all means, including shoot to kill," he said. Mr Putin held an urgent meeting with armed forces chiefs, top ministers and the heads of intelligence services to discuss Russia's response to the arrests.