The military prosecutor judge handling the case Saturday ordered police to find out where the Lutfallah II picked up the weapons and to whom they were being delivered.
The ship, which carried 11 crew members and flew the flag of Sierra Leon, was intercepted and detained by Lebanon as it sailed from Egypt to Syria. The Lebanese military said in a written statement the cargo of various weapons and ammunition was confiscated.
The Syrian owner of the ship and its Lebanese agent and a customs broker were also picked up.
The Daily Star said the chain-of-custody of the shipment was still murky Saturday but Syria's beleaguered government has alleged in the past that weapons were being smuggled into the country to supply rebel forces.
The Lebanese government has been adamant about staying out of the Syrian uprising and not allowing the country to become a conduit for supplies and the settling of scores.