Authorities are investigating whether the ship, which came into the port of Mariveles northwest of the capital, Manila, was transporting firearms to illegal syndicates, local warlords or rebel groups.
"These guns are the primary weapon of the Israeli army," Armand Balilo, a coast guard spokesman, said. "This is dangerous if it falls into the wrong hands."
|A map on the vessel showed it was headed towards a province south of the capital [EPA]
Leonilo de la Cruz, the regional police director, said the mostly Georgian crew did not speak English, and failed to provide any documentation to prove the cargo was legitimate.
"We're having a hard time talking to them," de la Cruz said, adding an interpreter would be helping investigations.
"They are either pretending they don't know how to speak English or they simply do not know how."
A map found on board showed the Panama-registered vessel had sailed from a port in Turkey bound for the Batangas province in the south, officials said.
The Philippines has been battling communists and Muslim separatists for decades in conflicts that have killed about 160,000 people.