Malaysian police have seized suspected bomb-making equipment on a ship bound from China to the Middle East.
The cargo, which was not declared, was held 10 days ago, police confirmed.
An investigator said the equipment might be for construction sites but if misused could be used to make a bomb.
Last year Malaysia passed a Strategic Trade Bill banning involvement in any trade of restricted items and Prime Minister Najib Razak said the law would be strictly enforced.
"I can confirm that we have seized the containers at Port Klang but we do not know yet whether these are possibly parts to help make weapons of mass destruction or nuclear items," national police chief Ismail Omar told AFP.
"We are waiting for a report from our nuclear agency on the parts seized before we can make any determination and investigations are still ongoing," he added.
Malaysia's Sun daily newspaper had reported that police had seized "parts of equipment believed used to make weapons of mass destruction, including nuclear warheads".
However, Mohamad Bakri Zinin, chief of the federal police's criminal investigation unit, said investigators were still trying to determine the equipment's specific destination.