RUSSIA has issued a stark warning over what it says is a build- up of Nato ships in the Black Sea, as tensions rise to their highest level since the outbreak of hostilities in Georgia.

The missile destroyer USS McFaul is already off the coast, with the US Coastguard ship Dallas docked in Georgia's port of Batumi, both to show support for the Caucasus nation. Washington has now ordered the flagship of its 6th Fleet, the sophisticated command ship Mount Whitney, into the area, saying it will deliver humanitarian supplies. But the flotilla has angered the Kremlin.

Dmitry Rogozin, the Russian ambassador to Nato, warned against western interference in Georgia's two breakaway regions, saying: "If Nato takes military actions against Abkhazia and South Ossetia, acting solely in support of Tbilisi, this will mean a declaration of war on Russia."

Meanwhile, Vladimir Putin, the Russian prime minister, dragged the United States presidential candidates into the row. He suggested Georgia might have been pushed by someone in the US into using force to protect the two separatist states, saying the anti-Moscow rhetoric would help give a competitive advantage to one of the candidates.

Colonel-General Anatoly Nogovitsyn, Russia's deputy chief of the general staff, claimed up to 18 Nato vessels were in, or expected to be in, the Black Sea, and he attacked the use of warships to deliver aid to Georgia as "devilish".

Three frigates - from Spain, Germany and Poland - sailed into the Black Sea eight days ago. They were joined later by a US frigate, the Taylor, for port visits and exercises off the coasts of Romania and Bulgaria. Four warships of Nato member Turkey are also in the Black Sea.

Mr Putin's spokesman said: "The appearance of Nato battleships here in the Black Sea basin ... and the decision to deliver humanitarian aid [to Georgia] using Nato battleships is something that can hardly be explained.

"Let us hope that we do not see any direct confrontation."

Russia claims the build-up is contrary to the 1936 Montreux Convention, which regulates the passage of warships there. But that charge has been denied by Carmen Romero, a Nato spokeswoman, who said the alliance had applied for transit into the Black Sea in June and stressed that the vessels would stay less than 21 days, as required by the convention.

"There is no Nato naval build-up in the Black Sea," she said. "Nato is conducting a routine and long planned exercise limited to the western part of the Black Sea.