DAMASCUS (AFP) -- Syria and Hezbollah rejected U.S. accusations they are trying to topple Beirut's pro-Western government, while Hezbollah countered that Washington is using Lebanon as a tool against Syria and Iran.

"The rumors put about by the U.S. administration according to which Syria, Iran and Hezbollah are seeking to destabilize the situation in Lebanon are wrong," a Syrian foreign ministry statement said.

The White House sounded the alarm over what it called "mounting evidence" that the Hezbollah were "preparing plans to topple" the Lebanese government. But spokesman Tony Snow refused to provide details or even describe the information underpinning the accusation, saying it was classified and that keeping the charge vague "serves a diplomatic purpose and an important one."

Reacting to the allegations, Hezbollah accused Washington of seeking to "turn Lebanon into a tool of the war of the (U.S. President George W.) Bush administration against those considered enemies".

"The latest American position is a blatant interference in a Lebanese internal affair concerning the Lebanese people's choices over their government and policies," a Hezbollah statement said.

Since its summer war with Israel, Hezbollah has called for the current Lebanese cabinet, in which it has two ministers, to be replaced with a national unity government including a Christian faction currently in opposition.

Hezbollah said "the American position is meant to obstruct the internal settlement sought by parties attempting to reach a comprehensive national solution.

Before the war with Israel, Hezbollah had been involved in cross-party talks, dubbed the national dialogue, on the most controversial outstanding issues still facing Lebanon -- its fighters' weapons and relations with Syria.

But since the conflict, Hezbollah leaders have issued increasingly strident condemnations of the pro-Western politicians opposed to Syria that head the current government.

France, which currently leads UN peacekeepers deployed in Lebanon as part of a UN-brokered truce agreement, said it had no details of any plan by Syria and Iran to destabilize Lebanon, but warned against any moves in that direction.

"We have no specific details of plans of that nature," foreign ministry spokesman Denis Simonneau said.

"France, for its part, reaffirms its support for the government of (Prime Minister) Fuad Siniora and for his efforts to stabilize Lebanon and permit the rapid reconstruction of the country," he said.

France was also instrumental, with the United States, in forcing Syria to withdraw military forces from Lebanon last year.

A Saudi diplomat, meanwhile, said secret contacts were underway with political forces in Lebanon to agree on a unity government in the interest of stability.

"The kingdom is making discreet contacts and holding talks, primarily though its ambassador in Lebanon Abdel Aziz Khuja, to placate the political situation in Lebanon," the diplomat said in Riyadh on condition of anonymity. Saudi was also working to "remove barriers to holding national dialogue talks as called for by parliament speaker Nabih Berri."

The diplomat did not rule out the possibility of "enlarging the current government, which would be a middle-of-the-road solution acceptable to all," adding that Saudi's priority was to "avoid escalating tensions within Lebanon."