Melita Sunjic, spokeswoman for the UN High Commissioner of Refugees in Georgia, told The Associated Press that although it was not clear if Russian soldiers were actually preventing refugees from returning, the warnings block them from going home.
"If they say 'we can't guarantee your safety,' you don't go," she said.
Some 2,000 refugees are at UNHCR camps in Gori, and thousands of others may in the region. They hope to return to villages in the so-called "security zones" Russia has claimed for itself on Georgian territory south of the border with the separatist republic of South Ossetia.
U.S. Senator Bob Corker, a member of the Foreign Relations Committee, visited Gori on Saturday to observe the distribution of US food aid.
The United States has sent substantial aid to Georgia in the wake of the war, using naval ships and military aircraft. Russian officials raised speculation that the military involvement could indicate the United States was seeking to restore Georgia's armed forces, which had received massive military aid from Washington in recent years.
Asked whether the United States was considering new military aid, Corker said "these subjects are part of a longer and midterm discussion" when Congress reconvenes in September.
Fighting broke out Aug. 7 when Georgian forces began heavy shelling of the South Ossetian capital, Tskhinvali, hoping to retake control of the province. Russian forces poured in, pushed the Georgians out in a matter of days and then drove deep into Georgia proper.
Under an EU-brokered cease-fire, both sides were supposed to return their forces to prewar positions, but Russia has interpreted one of the agreement's clauses as allowing it to set up 7-kilometer deep security zones, which are now marked by Russian checkpoints.
Refugees coming into Georgia from those zones say they are being terrorized, beaten and robbed by South Ossetians.
Georgia has severed diplomatic ties with Moscow to protest the presence of Russian troops on its territory. It claims, as does the West, that Russia is violating the EU agreement. The Georgian government announced Friday that diplomatic staff would leave Georgia's Moscow embassy Saturday, though Georgian Foreign Ministry spokeswoman Khatuna Iosana said they had not left as of 6:30 p.m. local time.
"We found ourselves in an awkward situation when a country militarily invading and occupying our country, then recognizing part of its territories, is trying to create a sense of normalcy" by maintaining diplomatic relations, Georgian Foreign Minister Eka Tkeshelashvili said in Sweden earlier.
Russia condemned the diplomatic cutoff, which will require Georgia and Russia to negotiate through third countries if they negotiate at all. That would make for a sticky situation because Russia sees Western nations as biased in Georgia's favor. Georgia, which had pushed for a greater role for international organizations, could see it as advantage.
But it may bring little change, because there were few signs of productive diplomacy even before the war.
Trade between Russia and Georgia is also minimal, following Russia's imposition in 2006 of bans on Georgia's major exports - wine and mineral water - and other products. Only a fraction of foreign investment in Georgia comes from Russia. A Russian ban on direct flights to and from Georgia was lifted this year but flights halted again when the war erupted.
Russia has faced isolation over its offensive in Georgia and its recognition of South Ossetia and Abkhazia. No other country has followed suit and recognized the regions' independence. The United States and Europe have condemned Russia's actions but are hard-pressed to find an effective response.
With European Union leaders set to huddle on how to deal with an increasingly assertive Russia, Prime Minister Vladimir Putin has angrily warned Europe not to do America's bidding and said Moscow does not fear Western sanctions.
Adding to the tension, a lawmaker in South Ossetia said Russia intends eventually to absorb the province.
South Ossetian parliamentary speaker Znaur Gassiyev said Friday that Russia will absorb South Ossetia within "several years" or even earlier. He said that position was "firmly stated" by both the province's leader, Eduard Kokoity, and Russian President Dmitry Medvedev in talks in Moscow earlier this week.
The statement stoked Georgian suspicion that Moscow's intent all along has been to annex South Ossetia.
In Moscow, a Kremlin spokeswoman said Friday there was "no official information" on the talks.
South Ossetia broke away from Georgia's central government during a war in the early 1990s, and many see integration into Russia as a logical next step for the province with closer ethnic ties to North Ossetia, in Russia, than with Georgia.