Russia warned today it would not allow Georgia to rearm amid signs that the government in Tbilisi had actively sounded out the Obama administration about rebuilding the military during a visit by the vice-president, Joe Biden, on the eve of the anniversary of last year's war.

Russia's foreign ministry said it would take "concrete steps" to prevent Georgia from rebuilding its military capability, and served notice that it would sever military co-operation with any country that supplied arms to Tbilisi. It said it was "deeply worried" Georgia was preparing for another conflict, as tensions continue to rise ahead of the 7 August anniversary of last year's brief war.

The stern warning from Moscow came after US officials indicated that Georgia's president, Mikhail Saakashvili, had asked Biden for US help to rebuild his armed forces following last year's crushing defeat by Russia. He had allegedly requested anti-tank and anti-aircraft weapons. Another US official later denied the request had formally been made. Any request for arms is likely to embarrass the White House at a time when it is attempting to reset relations with Russia. US officials also disowned earlier comments that Saakashvili asked Washington to send monitors to the tense border regions with South Ossetia and Abkhazia.

But Biden has made a point during his visit of reaffirming Washington's strong support for Georgia's territorial integrity and its attempts to join Nato. "We, the United States stand by you on your journey to a secure, free, democratic and once again united Georgia," he said, adding that the US would not recognise Georgia's Moscow-backed rebel republics.

He also recalled visiting Tbilisi during last year's conflict, as Russian bombs fell: "Instead of standing in your parliament I sat on a roof on top of a restaurant with President Saakashvili as the sound of artillery fire and fighter aircraft punctuated the night."

The US administration is currently holding talks with Russia over a new nuclear strategic arms reduction pact following Barack Obama's visit to Moscow two weeks ago. It is also seeking the Kremlin's cooperation on Iran, and logistical assistance for US troops in Afghanistan.

Today, however, the US vice-president made clear that any strategic accommodation with Moscow would not take place at the expense of Georgia, or other pro-western allies such as Ukraine. He also rejected Moscow's doctrine that it has "privileged interests" in post-Soviet states.

"I know there is some concern, and I understand it, that our efforts to reset relations with Russia will come at the expense of Georgia. Let me be clear: they have not, they will not and they cannot." Biden also called on Moscow to implement last August's ceasefire deal, which saw Russia's president Dmitry Medvedev agree to pull Russian troops back to their pre-conflict positions. Russia has since poured thousands of soldiers into both breakaway republics, arguing they are now sovereign entities. Most analysts are sceptical that Russia is planning a new invasion of Georgia. According to Yulia Latynina, writing in the Moscow Times, Obama received private reassurances from Russia's leaders during his recent Moscow summit that there would be no second conflict.

There is little prospect of a Georgian attack. Russian experts say Georgia's small army is no match for the strong Russian military grouping now sitting on the de facto border. Russia's forces include tanks, border troops and heavy ammunition.

"Russia doesn't want a new war at the moment. They have economic interests in Europe to consider," Natalia Leshchenko, a senior analyst at Global Insight said. "They would not want to do anything to worsen their standing with the US or Europe."

Biden was given a rapturous reception in Tbilisi, with hundreds of people waving Georgian and US flags as his motorcade sped past.