Malaysia questioned a Chinese-registered vessel suspected of looting two British World War II shipwrecks.
The ship was seized over the weekend after it anchored without a permit off Malaysia's southern Johor state, the Malaysian Maritime Enforcement Agency chief in the region, Nurul Hizam Zakaria, said on Tuesday.
Authorities found scrap metal and cannon shells on the ship.
"Our investigation is now directed to where these cannon shells originated from. Right now, we have officers from multi-agencies searching the big ship," Zakaria said.
The crew of 32 included 21 Chinese nationals, 10 Bangladeshis, and one Malaysian.
Wrecks targeted by scrap metal scavengers
Authorities believe the ammunition may be from the HMS Prince of Wales and HMS Repulse, which were sunk in 1941 by Japanese torpedoes days after the attack on Pearl Harbor.
The United Kingdom's Ministry of Defense condemned the "desecration" of maritime military graves.
The cannon shells could also be linked to artillery that was discovered at a jetty in Johor on May 19, the maritime agency said in a statement Monday.
Malaysia's New Straits Times newspaper reported in recent weeks that illegal salvage operators had targeted high-grade aluminum and brass fixtures from the two British warships.
mf/kb (AFP, AP, dpa)