* Interfax says two Russian warships head to Mediterranean
* Navy official says no plans to beef up forces
* U.S. is repositioning warships in Mediterranean (Adds details about ship movements)
By Timothy Heritage
MOSCOW, Aug 29 (Reuters) - Russia said on Thursday it was sending warships to the Mediterranean, but denied it was beefing up its naval force there as Western powers prepare for military action against Syria.
Interfax news agency quoted a source in the armed forces' general staff as saying Russia, Syria's most powerful ally, was deploying a missile cruiser from the Black Sea Fleet and a large anti-submarine ship from the Northern Fleet in the "coming days".
Any strengthening of the navy's presence could fuel tension, especially as the United States has said it is repositioning naval forces in the Mediterranean following an alleged chemical weapons attack which it blames on Syrian government forces.
"The well-known situation now in the eastern Mediterranean required us to make some adjustments to the naval force," the source said in a reference to the events in Syria.
It was not clear when the vessels would arrive but Interfax said the missile cruiser Moskva was currently in the North Atlantic and would set sail in the next few days.
President Vladimir Putin has said the naval presence is needed to protect national security interests and is not a threat to any nation. Russia cooperates with NATO navies against piracy and its ships call at Western ports.
The navy later said a deployment was imminent in the Mediterranean but suggested it would not increase the size of Russian forces there.
"This is not a new group ... but a planned rotation," the state-run RIA news agwency quoted an unnamed naval official as saying.
Confusion has at times surrounded Russian deployments in the Mediterranean because of the secrecy involved.
Both RIA and Interfax later quoted the Defence Ministry as saying that in the rotation, to be conducted from Sept. 1-7, a destroyer and two landing ships would replace a frigate and three landing ships in the Mediterranean.
Separately, the Defence Ministry website said the Moskva, which Interfax had reported was headed to the Mediterranean, was leaving Venezuela but would remain in the Atlantic for now.
Washington accuses Syrian government forces of carrying out last week's chemical weapons attack and has made clear it could soon launch a military strike.
Russia is one of Assad's biggest arms suppliers. It opposes any military intervention in Syria and has shielded Damascus against further sanctions at the U.N. Security Council.
Defence experts said the deployment of the two warships identified by Interfax could give Assad early warning of cruise missile launches, particularly by submarine, or jam radars or navigation systems, although they might never be used for this.
"What we may be seeing here is an example of gunboat diplomacy rather than a deliberate attempt to interfere directly in any coalition strike militarily," said Lee Willett, editor of IHS Jane's Navy International.
"The simple presence of any ships will have an impact politically, and that is the primary intent."
Russia's chief of staff said in June the navy had stationed 16 warships and three ship-based helicopters in the Mediterranean, its first permanent naval deployment there since Soviet times. (Additional reporting by Peter Apps in London and Steve Gutterman in Moscow; editing by Andrew Roche)