Syrian rebel gunmen in inflatable dinghies have attacked a military unit on the Mediterranean coast, with deaths on both sides, state media report.
It is thought to be the first rebel assault from the sea. Separately, Lebanon says its navy has seized weapons destined for the rebels.
Clashes between security forces and deserting troops left heavy casualties near Damascus and Aleppo, reports say.
The violence comes despite a shaky ceasefire in force since 12 April.
On Thursday UN Secretary General Ban Ki-moon warned that Syria’s government was “in contravention” of a UN- and Arab League-backed peace plan.
Clashes Saturday’s violence came after the Lebanese navy said it had found and confiscated three containers full of arms and ammunition bound for the rebels.
The ship, the Lutfallah II, is reported to have begun its voyage from Libya, stopped off in Alexandria in Egypt, and then headed for the port of Tripoli in northern Lebanon before it was intercepted.
The BBC’s Jim Muir in Beirut says it is believed the consignment was destined for the rebels in Syria, with whom the new Libyan regime strongly sympathises.