Lebanese authorities have impounded a ship after a large consignment of arms and ammunition were found on board.
Eleven crew members of the Lutfallah II have been detained.
It is believed the consignment was destined for rebels in Syria and was due to unload in Tripoli in northern Lebanon.
Lebanon said it had intercepted three containers of heavy machine guns, artillery shells, rockets, rocket launchers and other explosives destined for rebel forces on a ship originating in Libya.
Syrian authorities have repeatedly charged that weapons are being smuggled from Lebanon to rebels.
Yesterday, government newspaper Tishrin wrote that UN Secretary-General Ban Ki-moon "avoids talking about abuses by armed groups and focuses his blame solely on Syria, as usual. He encourages these groups to continue to commit more crimes and terrorist acts."
The Russian foreign ministry said "we are convinced that the terrorists operating in Syria need a decisive rebuff, and that all domestic and outside players need to prevent any support" from reaching the rebel forces.
Government troops killed at least ten rebel fighters in the Damascus region on Saturday, the Syrian Observatory for Human Rights said.
22 civilians also died - eight in flashpoint central Hama, two in nearby Homs, three in Idlib near the Turkish border, four in Aleppo, four in Damascus province and one in Al-Raqqah in the northeast.
Separately, the official SANA news agency reported three soldiers and two "terrorists" killed in Syria's second-biggest city Aleppo in clashes between troops and "armed terrorist groups."
An activist said the fighting began as "officers and soldiers of a military base near the presidential palace... deserted with their weapons."
Meanwhile, in what is believed to be the first case of Westerners going missing in the violence-swept country, Budapest said two Hungarians had been kidnapped.
Reports from Syria cannot be independently verified as state authorities have barred international journalists and rights groups.
A truce of sorts, which technically came into effect on 12 April, has taken a daily battering, and the European Union on Friday expressed extreme concern about the persistent bloodshed.
The latest violence came as veteran Norwegian peacekeeper Major General Robert Mood was en route for Syria to take the helm of a fledgling monitoring mission after being appointed by Mr Ban, diplomats said.
General Mood takes over a mission already facing major obstacles before the full 300-member force approved by the UN Security Council has even gathered.
He has himself highlighted the "abyss of suspicion" between President Bashar al-Assad and the opposition, in the face of an uprising that has killed more than 9,000 people since March 2011, according to UN figures.