Malaysian customs authorities said they have seized unprocessed heroin worth $12 million from a cargo ship from Pakistan.

A Customs Department representative said officials found 475 pounds (215 kilograms) of the drug stashed in 278 cement bags aboard a vessel at the western Malaysian harbor of Northport. The discovery occurred in late April but was only made public this week.

The official said the vessel transported the heroin from Karachi. He spoke on condition of anonymity Saturday because he was not authorized to make public statements.

The New Straits Times newspaper said police arrested two Pakistanis suspected of involvement in the smuggling.