A US Navy destroyer carrying relief supplies arrived at a port in Georgia on Sunday in a sign of US support for its ally as Russian troops dug in further up the coast.

Moscow faced renewed pressure to withdraw its forces from western Georgia, where they control access to the key Black Sea port of Poti. They also held positions around South Ossetia.

In further fallout from the five day conflict, a train carrying fuel from Azerbaijan exploded just west of Gori in central Georgia, sending a thick black tower of smoke billowing into the air.

Georgia's interior ministry said the rail track, a vital east-west link across Georgia, had no casualties were reported.

The USS McFaul dropped anchor off Batumi, 50 kilometres south of Poti, the first of three ships carrying blankets, food and other supplies to help Georgia deal with an estimated 100,000 displaced people.

A top Russian general on Saturday accused NATO countries of using humanitarian aid as "cover" for a build-up of naval forces in the Black Sea, heightening tension in the aftermath of the conflict.

Russia withdrew tanks, artillery and hundreds of troops from their most advanced positions in Georgia on Friday, saying it had fulfilled all obligations under a French-brokered peace agreement.

But Russian troops still control access to the western port of Poti, south of the Moscow-backed rebel region of Abkhazia, and have established other checkpoints around South Ossetia, where the confict began.

Acting as head of the European Union, French President Nicolas Sarkozy telephoned his Russian counterpart Dmitry Medvedev on Saturday and asked him to withdraw his forces from a road linking Poti to Senaki in western Georgia.

Sarkozy and Medvedev agreed on the need for an "international mechanism" in the area south of South Ossetia, a French statement said.

The Kremlin said it was ready to cooperate with the Organisation for Security and Cooperation in Europe (OSCE) to monitor a buffer zone near South Ossetia, but it said there had been no discussion about replacing Russian troops by international monitors.

"During the telephone conversation between the Russian and French presidents, there was no discussion about replacing Russian peacekeeping troops by an OSCE mission in the buffer zone," said a Kremlin spokesman.

The West sees the presence of OSCE monitors as critical to ensuring the success of the ceasefire.

Desperate for peace

The vague six-point peace plan has been interpreted differently by Russia and the West, with Russian claiming it has the right to leave peacekeepers deep inside Georgia.

France, Britain, the United States, NATO and other Western powers have demanded Russia pull back further. An AFP reporter saw Russian troops holding at least six positions in an 80-kilometre area around the Black Sea port city of Poti on Sunday.

A senior Georgian official said Russian forces were also maintaining eight positions around the separatist region of South Ossetia in central Georgia, including one a few kilometres from Gori on the main road into the region.

"No withdrawal has been mentioned today. The Russians are keeping all their previous illegal checkpoints," Georgian National Security Council secretary Alexander Lomaia told AFP.

Russian troops poured into Georgia on August 8 to repel a Georgian attempt to regain control of the breakaway region of South Ossetia, which is backed by Moscow.

After smashing Georgia's small US-trained army in South Ossetia, Russian troops then fanned out through Abkhazia, another pro-Moscow breakaway region in the west, and pushed far into Georgian territory.

Moscow retains full control of Abkhazia and South Ossetia and says it has the right to establish a buffer zone beyond taking in stretches of the main east-west highway linking Tbilisi to Poti.

The speedy military victory over Georgia, which is pressing for membership of NATO, stunned Western powers and plunged relations between Russia and the West to their lowest point since the end of the Cold War.

Ukrainian President Viktor Yushchenko called on Sunday for stronger efforts for his country to join NATO, saying Ukraine shares Georgia's "pain" in its conflict with Russia.

"We must intensify our work to win membership in the European security system and strengthen the defence capabilities of our country," Yushchenko said in a speech marking the 17th anniversary of Ukraine's independence from the Soviet Union.