Russia’s defence ministry has said that Georgia was planning a “major provocative act” in the Georgian town of Gori, Russia’s RIA news agency has reported.

Russian troops pass destroyed buildings in the South Ossetian capital Tskhinvali

It followed Moscow saying its forces will begin withdrawing from its neighbour’s territory at midday tomorrow.

News of the pull-out came from France’s President Nicolas Sarkozy, who has spoken to Russian President Dmitry Medvedev by phone.

It emerged just hours after conflicting reports about whether Russia’s military is moving out of Georgia’s breakaway region of South Ossetia.

A military commander - Major General Vyachislav Borisov - said troops had started to head home.

But a Russian Defence Ministry spokesman said: “It has not started yet. The question of withdrawal is being considered now and the decision will be taken as the situation in the region is stabilised.

“What is going on is probably just preparation, not actual withdrawal.”

The denial follows claims that Russia has been digging into its positions despite President Dmitry Medvedev agreeing a ceasefire in the face of Western pressure.

There were reports that Russian troops were building ramparts around tanks and posting sentries on a hill in central Georgia.

The US and France said it appeared that Russia was defying the truce already.

In his phonecall, President Sarkozy told Mr Medvedev there would be “serious consequences” if Russia failed to pull out soon.

It is believed that Russian forces still control two Georgian cities and the key east-west highway between them.

US secretary of state Condoleezza Rice said: “From my point of view - and I am in contact with the French - the Russians are perhaps already not honouring their word.”

Russia’s foreign minister, Sergei Lavrov, said Mr Medvedev had signed the ceasefire deal and ordered its implementation, but would not withdraw troops until Moscow was satisfied that security measures allowed under the agreement were effective.

He said Russia would strengthen its peacekeeping contingent in South Ossetia, the separatist Georgian region at the centre of more than a week of warfare that has soured relations between Moscow and the West.

US President George Bush has warned Russia that it cannot lay claim to the two separatist regions in US-backed Georgia, even though their sympathies lie with Moscow.

Georgia’s foreign ministry has accused Russian army units and separatist fighters in one of the regions, Abkhazia, of taking over 13 villages and the Inguri hydropower plant, shifting the border of the Black sea province toward the Inguri River.

The villages and plant are in a UN-established buffer zone on Abkhazia’s edge, and it appeared that the separatists were bolstering their control over the zone after Russian-backed fighters forced Georgians out of their last stronghold in Abkhazia earlier this week.

The peace pact calls for both Russian and Georgian forces to pull back to positions they held before fighting erupted in South Ossetia on August 7.

Meanwhile, David Cameron has called on the Government to hit back at Russia over the invasion of Georgia by barring the wealthy Moscow elite from enjoying their luxury shopping weekends in London.

The Tory leader, who yesterday flew into the Georgian capital Tbilisi in a show of support for the beleaguered Caucasus republic, urged ministers to tighten the visa restrictions on Russian nationals visiting the UK.

He wrote in the Sunday Times: “Russia’s elite value their ties to Europe - their shopping and their luxury weekends. We should look at the visa regime for Russian citizens.

“Russian armies can’t march into other countries while Russian shoppers carry on marching into Selfridges.”

In another article, in the Sunday Telegraph, General Sir Mike Jackson, former head of the British armed forces, said the West should make more of an effort to understand Russia’s point of view.

He wrote: “The ‘Near Abroad’ - the countries bordering Russia - are strategically vital to its security.

“For me, the right course for the West - without compromising its own position and values - is to show a greater understanding of why Russia behaves as it does, to accept more willingly Russia’s concerns for its Near Abroad.”