Georgia signed a ceasefire agreement seeking to end its conflict with Russia, whose forces still occupied parts of Georgian territory, as the United States demanded their immediate departure.

Sponsors of a UN Security Council resolution to formalize the ceasefire deal meanwhile pushed for a vote by week's end, but Moscow balked at inserting any reference to Georgia's territorial integrity.

Georgia's pro-Western President Mikheil Saakashvili announced he had signed the EU-brokered ceasefire during a visit to Tbilisi by US Secretary of State Condoleezza Rice.

"With the signing of this accord, all Russian troops, and any paramilitary and irregular troops that entered with them, must leave immediately," Rice said in Tbilisi.

Despite the accord, thrashed out by French President Nicolas Sarkozy earlier this week, Russian armoured vehicles and tanks remained deep inside Georgian territory, some even pressing further towards the capital.

Rice, whose visit to Tbilisi was seen as a show of support for Saakashvili's government, criticised the Russians for not honouring their promises to halt military operations in Georgia.

"The verbal assurance that President (Dmitry) Medvedev gave that Russian military operations had stopped... clearly was not honoured," Rice said.

Russian Foreign Minister Sergei Lavrov promised Rice that Russia would "faithfully" implement the ceasefire accord, an American official said.

Scores of Russian armoured vehicles were concentrated at a base outside Gori, a strategically key town half-way between Tbilisi and the breakaway Georgian province of South Ossetia at the centre of the conflict.

An AFP reporter late Friday saw a convoy of 10 Russian armoured personnel carriers move from Gori before stopping in a position just 40 kilometres (25 miles) from Tbilisi.

At the UN, a Western diplomat close to the bargaining involving European, US and Russian diplomats told AFP: "Yes ideally, we would like a vote (formalizing the ceasefire) this weekend.

"But we'll take as long as it takes. We are not going to push for a vote if we know that the Russians will veto the text -- which does not mean we have to give in to all their demands... There has to be hard bargaining," said the diplomat, who spoke on condition of anonymity."

And UN chief Ban Ki-moon was to interrupt his current two-week vacation Saturday to hold private talks with the ambassadors of the United States, Russia and Georgia, according to a UN official.

US President George W. Bush meanwhile complained of Moscow's "bullying" and called on Russia to honour its pledge to withdraw its troops.

"Bullying and intimidation are not acceptable ways to conduct foreign policy in the 21st century," he said, adding that Russia had damaged its credibility with the West by its offensive against Georgia.

"Moscow must honour its commitment to withdraw its invading forces from all Georgian territory," Bush said outside the Oval Office.

Russian troops entered Georgia in response to a Georgian offensive on August 7 to retake South Ossetia, which broke away in the 1990s.

Russia strongly supports South Ossetia and the second breakaway region of Abkhazia and has given Russian passports to most people in the territories.

"A significant part of Georgian territory remains under foreign military occupation," Saakashvili, red-faced with emotion, said alongside Rice.

"Never, ever will Georgia reconcile itself with the occupation of even one square kilometre of its territory."

A US official, who asked not to be named, said that Russia was now expected to itself sign the agreement as Saakashvili had put his name to it.

Medvedev told Sarkozy in phone talks that his country will sign the ceasefire accord and scrupulously respect all agreements, including a troop withdrawal, the office of the French president said.

Rice said that the United States favoured the deployment of a "neutral" international peacekeeping force in Georgia.

As tensions flared between Moscow and Washington, Medvedev also clashed over the crisis with German Chancellor Angela Merkel during talks at the Black Sea resort of Sochi.

While he renewed his support for South Ossetia and Abkhazia, she slammed the Russians for their "disproportionate" use of force and said the territorial integrity of Georgia must be a "basic point" in any plan for restoring peace in the Caucasus.

Medvedev said the separatist regions could not live under Georgian control again.

Two more US military transports flew to Georgia Friday with medical and other humanitarian supplies, US officials said.

Experts from the US Agency for International Development (USAID) began arriving Friday to assess the needs of the war-torn country, joining a US military assessment team that arrived the day before, officials said.
Armed gunmen held up UN workers in Gori Thursday and stole their vehicles and aid agencies have complained of the difficulty of bringing aid to areas where it was needed most.

The latest estimate by the UN High Commissioner for Refugees put the number of displaced people in the conflict region at more than 118,000.

A convoy of Russian