A spokesman for the Georgian government has accused Russia of launching an online attack against the country’s web infrastructure in conjunction with its occupation of South Ossetia.

Shortly after Russian tanks crossed the border into Georgian territory, the Georgian government web site started to suffer a denial of service attack, the official said.

Then a number of key government web sites were taken down or defaced, including one incident where a picture of Georgian president Mikheil Saakashvili was replaced with one of Adolph Hitler.

"A cyber warfare campaign by Russia is seriously disrupting many Georgian websites, including that of the Foreign Affairs Ministry," the Georgian Foreign Ministry said in a statement.

However, the Russian government is denying any attacks and told Reuters that it was suffering attacks of its own.

"On the contrary, a number of internet sites belonging to the Russian media and official organisations have fallen victim to concerted hacker attacks," a Kremlin spokesman said.

This is not the first time Georgia has come under online attack. Last month the official site of Georgia's president was taken down by attacks for two days.