Beirut - Lebanese authorities say they have uncovered a Syrian plot to destabilise Lebanon in an investigation that has led to the indictment of a top Syrian official and compounded fears that Damascus aims to export its civil conflict next door.
The indictments issued in Beirut against two Syrian officers, including General Ali Mamlouk, mark an unprecedented Lebanese move against a more powerful neighbour that has been a major player in the country's affairs for decades.
If confirmed, the alleged plot drawn up in collaboration with a former Lebanese minister to ignite sectarian strife in Lebanon would represent a major blow to Syria's Lebanese allies, including Hezbollah.
A formal indictment from the military prosecutor issued on Saturday accused Michel Samaha, the Lebanese politician in question, Ali Adnan, a Syrian colonel, and General Mamlouk, head of the Syrian national security bureau, of forming an "armed gang" that planned to detonate bombs prepared by the Syrians with the aim of "inciting sectarian fighting" in Lebanon.
The indictment said their targets included politicians and religious figures - a charge evoking political violence that has cost the lives of numerous Lebanese leaders over the years, including statesman Rafik al-Hariri, who was killed in 2005.
Though Syria's critics routinely accuse it of stirring trouble here, they said this could be a rare case of the Lebanese uncovering evidence of a Syrian role in destabilising their country - for decades an arena for proxy conflicts waged by regional and international powers.
The Syrian government has not commented on the case.
The security agency which uncovered the alleged plot said it had found large quantities of explosives and money "set aside for the execution of the terrorist acts". A Lebanese politician with ties to the Damascus administration confirmed media reports that Samaha had confessed during questioning.
"This is a great blow for us, the ones who are defending the Syrian regime," said the pro-Syrian politician, part of the "March 8" alliance dominated by the Shi'ite, Iranian-backed Hezbollah, a powerful armed group and political party.
Hezbollah has said little on the case.
In 2007, Samaha was named on a White House-issued list of Lebanese and Syrian figures suspected of working to undermine Lebanon's stability and the Western-backed Beirut government in office at the time.
The civil war in Syria, where the Alawite-led administration is fighting an opposition dominated by Sunni Muslims, has shaken Lebanon's own sectarian balance, triggering fighting between Sunnis and Alawites in the northern city of Tripoli.
A security source familiar with the investigation has said the plan was focused on northern Lebanon - mostly home to Christians, Sunni Muslims and Alawites.
Lebanon also has a large Shi'ite population and the country's sectarian politics triggered Sunni-Shi'ite violence in recent years. During a short civil conflict in 2008, followers of Hezbollah and the Shi'ite Amal party fought supporters of Saad al-Hariri, a Saudi-backed, Sunni politician.
Seeking to insulate Lebanon from the Syria crisis, the government led by Prime Minister Najib Mikati has adopted a policy of neutrality.
In a statement on the investigation, Mikati said: "We will not permit anyone to interfere in our affairs, or to turn Lebanon once again into an arena for score-settling or the export of foreign crises."
The investigation has triggered calls among Syria's opponents in Lebanon for the expulsion of the Syrian ambassador.
"This is very serious incident in the history of Lebanese-Syrian relations. It reveals the policy of the Syrian regime towards Lebanon, particularly its recourse to crimes and terrorism to realise its political goals," said Boutros Harb, an MP and part of the anti-Syrian "March 14" alliance.
Harb was himself the target of an assassination attempt last month. He accused Hezbollah of protecting the would-be assassins, who planted a bomb in the elevator in his office block. Hezbollah denied any link to the incident.
Lebanese Foreign Minister Adnan Mansour told Reuters the issue was still in the hands of the judiciary. "Let us wait for what emerges from the judiciary," he said.