Gonzalo R. Gallegos, the U.S. State Department's acting deputy spokesman, said Washington was “urging Moscow to press South Ossetia’s de facto leaders to stop firing.”

“We’re urging Tbilisi to maintain restraint,” he added. "We’re very concerned about the situation. We call for an immediate end to the violence and for direct talks between the parties,” he said at a press briefing in Washington.

When asked if he thought the South Ossetian side had started the fighting, the U.S official responded: “We think it’s important that both sides stop firing, that they sit down and they discuss this in a peaceful manner.”

Meanwhile, Yuri Popov, the Russian Foreign Ministry’s special envoy and chief negotiator on South Ossetia, told Interfax news agency that the international community should reconsider Georgia’s NATO ambitions. Tbilisi, he said, cannot be trusted.

“Georgia's actions are absolutely incomprehensible and show that the Georgian leadership has zero credit in terms of trust,” Interfax quoted Popov as saying.