Malaysian authorities say they have detained the crew of a North Korean-registered freighter after the vessel anchored illegally in the nation's waters while flying the Malaysian flag upside down.

Officials say maritime enforcement officers investigated the MT Yong An after spotting it anchored off Malaysia's southern coast Saturday with the improperly flown flag. They said the ship's crew had failed to inform authorities that they were passing through Malaysian waters.

Officials said the ship was manned by 10 Indonesians, one Sri Lankan and one Chinese. They said the captain could face up to two years in prison if it is found that he flew the flag upside down deliberately.