SOCHI/TBILISI (Reuters) - Russia signed a peace deal to end the conflict in Georgia on Saturday but said “extra security measures” were needed before it could begin withdrawing its troops.

The blowing-up of a key rail bridge, blamed by Georgia on Russian forces, forced Azerbaijan to suspend oil exports by railway to ports in western Georgia -- a reminder of the sensitivity of the conflict in a key energy transit region.

President Dmitry Medvedev added his signature to a French peace plan already endorsed by Georgia and by leaders of its two rebel regions of South Ossetia and Abkhazia.

President George W. Bush said it was a “hopeful step” but that Moscow must now pull its forces out. France said the peace deal did not allow Russia to occupy Georgian towns.

But Russian forces continued to move around in parts of Georgia far outside Abkhazia and South Ossetia, the flashpoint that triggered a six-day war between the two countries.

Georgia’s foreign ministry accused Abkhazian “armed gangs” and Russian army units of occupying more than a dozen Georgian villages south of the Abkhaz border, as well as a hydro power plant on the Enguri river.

“There are cases of physical abuse and looting,” it said.

The ministry said Russian military aircraft had also dropped bombs to set fire to large areas of Georgian forest. No independent verification was immediately available.

Russian Foreign Minister Sergei Lavrov said withdrawal of Moscow’s forces would depend on extra security measures ordered by Medvedev, the nature of which was not made clear.

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Asked how long the withdrawal might take, Lavrov told reporters: “This does not just depend on us”. He blamed the difficult situation on the ground for delays.

SARKOZY LETTER

The French-led agreement drafted this week authorizes Russian forces to take “additional security measures” on a temporary basis pending the arrival of international peacekeepers, which requires a U.N. Security Council resolution.

However, French President Nicolas Sarkozy wrote in a letter to Georgian President Mikheil Saakashvili that this did not allow for a Russian military presence in any “major urban centre” of Georgia.

“These ‘additional security measures’ can only be implemented in the immediate proximity of South Ossetia, to the exclusion of any other part of Georgian territory,” he wrote.

Russian troops withdrew from an area 45 km (30 miles) from the Georgian capital on Saturday afternoon and a foreign military observer said it appeared a partial pullout might be underway, although that was not officially confirmed.

The United States has demanded that Russia leave Georgia immediately, accusing Moscow of “bullying” its tiny southern neighbor by sending in troops and tanks.

A simmering conflict between the two states erupted into war nine days ago, when Tbilisi launched an assault to retake breakaway, pro-Russian South Ossetia, prompting a crushing counter-offensive from Moscow.

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BRIDGE DESTROYED

Violence on the ground continued.

Georgia accused Russian troops of severing the country’s main east-west train link on Saturday by blowing up a railway bridge in broad daylight. Russia denied responsibility, saying it regarded hostilities as over.

“We are now in peacetime. Why should we be blowing up bridges when our job is to restore?” said Colonel-General Anatoly Nogovitsyn, deputy chief of the General Staff.

One end of the bridge, near the town of Kaspi, lay collapsed on the riverbank in a pile of rubble and twisted steel, Reuters television pictures showed.

Azerbaijan said the bridge’s destruction had forced it to suspend oil deliveries to the Georgian Black Sea coast. A pipeline running from the Caspian Sea to Russia’s Black Sea port of Novorossiisk is Azerbaijan’s only oil export outlet.

A Reuters television crew interviewed villagers who said men in military uniform arrived by jeep, uncoiled wires and detonated a device remotely to bring down the bridge, blowing out windows in nearby houses.

The villagers blamed Russian forces but the identity of the attackers could not immediately be verified. Irregular militias, based in South Ossetia, have also been operating against Georgian targets in recent days.

Despite the peace deal, a gulf still separates Moscow and Tbilisi over the future of the rebel regions, which broke away from Georgia in the early 1990s and declared independence, albeit without international recognition.

Bush echoed the Georgian position on Saturday, saying South Ossetia and Abkhazia were part of Georgia “and there’s no room for debate on this matter”.

But Lavrov has already told the West to “forget about Georgia’s territorial integrity”, saying the facts on the ground dictate a different reality.

Russia says 1,600 civilians died when Georgia stormed South Ossetia, though the figure has not been independently verified. Georgia says at least 175 people have been killed and hundreds more injured. The figure does not include South Ossetia.