"There is a crisis in ties with the Syrian government, with Lebanon the main reason," a Saudi official told AFP news agency, asking not to be named.

Lebanon's political instability stems from a stalemate between the Saudi-backed government and Iranian-backed opposition over the election of a new president. Saudi Arabia has been actively involved in trying to end Lebanon's gravest political crisis since the 1975-1990 civil war, with parliament paralyzed in a power struggle between the government and the opposition.

"Damascus has not joined in efforts, including the Arab initiative, to elect a consensus president" in Lebanon, which has been left without a head of state since November amid deadlock between pro- and anti-Syrian camps, he said on Thursday.

The Arab League plan calls for the election of army chief General Michel Suleiman as consensus president, followed by the formation of a national unity government in which no single party has veto power, and a new electoral law.

Despite agreement on Suleiman, the league has failed to nail down an accord on power-sharing in a new government between the Western- and Saudi-backed parliamentary majority and the opposition, supported by Damascus and Tehran.

"I call on all those with influence to help with the success of the Arab initiative," Saudi Foreign Minister Prince Saud al-Faisal said on Wednesday from Buenos Aires, in an indirect reference to Damascus. He warned that Lebanon was "on the verge of civil war."

A member of Saudi Arabia's appointed consultative council, Muhammad al-Zulfa, recalled that the 2005 assassination of Lebanon's former premier Rafiq Hariri, who also held Saudi nationality, had affected ties with Damascus. Syria has repeatedly fought off charges that it was behind the killing.

"The situation is worsening, as the kingdom believes the Syrian government is blocking efforts to settle the Lebanese crisis, especially with the Arab plan which had passed ... with Syria's accord," he said. Zulfa explained that Saudi Arabia was "upset at Iran's growing influence in Lebanon and the region at the expense of Arab interests, with Syria's help."

In light of the fallout of the political crisis having damaged relations between the two countries, Riyadh advised Saudis Monday against travel to Lebanon and for those already there to be cautious when moving around.

"The foreign ministry has advised citizens not to travel to Lebanon due to the unstable political and security conditions it is passing through at the moment," said a statement carried by the official Saudi Press Agency.

Behind the scenes of the political crisis in Lebanon lurks the international tribunal being set up to establish the truth behind the Hariri murder, said Saudi academic Khalid al-Dakhil, adding "Damascus defines its relations with other countries on the basis of their attitude toward the tribunal. And because Riyadh favors setting up the trial the Syrian regime sees this as an unfriendly stance, even hostile."

An Arab diplomat said Syria was "accusing Saudi Arabia of trying to internationalize the Lebanese crisis" by supporting the Hariri tribunal, which Syria fears could pin the blame on Lebanon's eastern neighbor. Damascus believes Prince Saud's recent tour of several Western capitals, including Washington and Paris, was aimed at speeding up the establishment of the tribunal, said the diplomat posted in Riyadh.

Oil-rich Saudi Arabia, Kuwait and the United Arab Emirates have informed the Beirut government they will soon pay their contributions toward financing the tribunal, according to a senior Lebanese official.

Ahead of the March 29-30 summit in Damascus, Saudi Arabia has not even received an invitation from Syria even although the Gulf state currently holds its rotating presidency.

Zulfa said the kingdom was unlikely to take part at a high level unless Syria changes its stand on Lebanon, where it was the key powerbroker before the Hariri murder led to a Syrian military pullout after a three-decade deployment. "It's possible the summit will not take place at all or only before a handful of heads of state," said Dakhil.

The Saudi academic said Lebanon could be left without a president for a long time yet "unless Syria secures an arrangement on the international tribunal ... its biggest worry." But the Arab diplomat ruled out a Saudi compromise on the Hariri probe, leaving little scope for healing the rift between Damascus and Riyadh.

Syrian Foreign Minister Walid Muallem said earlier this month that he hoped the Lebanon deadlock would be resolved by the time his country hosts the summit. "Syria supports the Arab initiative as an overall plan which would be implemented by consensus between the Lebanese," he said.

Relations between Riyadh and Damascus chilled after the 2005 assassination of five-times Lebanese premier Rafiq Hariri, a close Saudi ally – an attack widely blamed on Syria. Relations deteriorated further in 2006 when Saudi Arabia implicitly accused the Syrian- and Iranian-backed Shiite militant group Hezbollah of provoking that summer's war with Israel.