Two Russian lorries which were carrying military equipment were impounded.

Relations between Georgia and Russia have become increasingly strained over the last few weeks as the situation in the breakaway region deteriorates.

Last week, talks between the three sides to try to find a solution to the 12-year conflict broke down.

Georgia's new President, Mikhail Saakashvili, refused to take part in any talks, until South Ossetia released three Georgian officers detained earlier.

'Serious concern'

Russia and Georgia share a peacekeeping role in the South Ossetia region.

Such a large number of arms cannot possibly be used for peacekeeping purposes Valery Tserodze Georgian interior ministry spokesman

The head of the Russian contingent, Maj Gen Svyatoslav Nabzdorov, said the convoy had been stopped by Georgian officials near the South Ossetian village of Kurta late on Tuesday.

Eight of the 10 vehicles were released. The two that were loaded with weapons - including more than 100 missiles - were sent to Tbilisi.

The equipment was destined for a helicopter unit that all three sides considered necessary, Maj Gen Nabzdorov said.

But a Georgian interior ministry spokesman said the large number of weapons on board did not correspond with Russia's peacekeeping duties in the area.

SOUTH OSSETIA Population: Approximately 70,000 Capital: Tskhinvali Major languages: Ossetian, Georgian, Russian Major religion: Christianity Currency: Russian rouble, Georgian lari Profile: South Ossetia

Moscow argued that Georgia had earlier agreed to allow the shipment into the peacekeeping zone.

"Georgia's moves cannot be qualified as anything but a provocation," Russian defence ministry spokesman, Vyacheslav Sedov, said.

Moscow's foreign ministry has expressed "serious concern" over the incident.

Central control

Moscow says it wants to help broker a peaceful solution, but many people in Georgia suspect the Russians of siding with the separatists, says the BBC's Chloe Arnold in Tbilisi.

South Ossetia broke away from Georgia in the 1990s, after a war that followed the collapse of the Soviet Union.

It claimed independence from Georgia and wants to join North Ossetia, which is ethnically similar and part of Russia.

President Saakashvili has vowed to bring Georgia's breakaway regions back under central control.