Russian President Dmitry Medvedev signed treaties with Georgia's South Ossetia and Abkhazia yesterday that commit Moscow to defend the breakaway regions from any Georgian attack.

The treaties formalise military, diplomatic and economic cooperation between Moscow and the separatist regions, which Russia recognised as independent states after its brief war with Georgia last month.

In Tbilisi, a senior Georgian diplomat said Russia had annexed sovereign Georgian territory, and a US State Department official said Russia should honour previous commitments it had made to Georgia's territorial integrity.

Western states accused Russia of a disproportionate response after it sent its troops into Georgia last month and then recognised the two regions.

Moscow said it had a moral duty to act to defend them from what it called a genocide by Georgia's military in South Ossetia, which had tried to retake the region by force.

"The documents we have signed envisage that our countries will jointly undertake the necessary measures for counteracting threats to peace... and opposing acts of aggression," Mr Medvedev said after a lavish signing ceremony in the Kremlin.

"We will show each other all necessary support, including military support," Mr Medvedev said.

"A repeat of the Georgian aggression... would lead to a catastrophe on a regional scale, so no one should be in doubt that we will not allow new military adventures."

Western states have angered Russia by backing Georgia over the conflict. The Russian Foreign Ministry yesterday accused Nato of Cold War thinking after the alliance held high-level talks in Tbilisi this week.