KUALA LUMPUR, MALAYSIA - Human trafficking and drug smuggling have replaced pirate attacks as the leading crime threat off Malaysia's long coastline, a top maritime official said Monday.

"Piracy has been gradually reduced. But the main challenges (now) are smuggling of humans and there is also the smuggling of drugs," said Admiral Mohamad Amdan Kurish of the Malaysia Maritime Enforcement Agency.

"That needs to be checked. Last year we scored a major drug bust, there was an attempt to bring in 200 kilograms (440 pounds) of ganja (marijuana) from the Golden Triangle," he told reporters.

The Golden Triangle, second to Afghanistan as Asia's top drug-producing region, straddles the borders of Myanmar, Laos and Thailand.

Amdan attributed the problems to Malaysia's long coastline and extensive mangrove swamps which hamper security patrols and provide smugglers with hideouts to launch their illegal operations.

More than 30 percent of world trade and half the world's oil shipments pass through the Malacca Strait, which is shared by Malaysia, Indonesia and Singapore.

It was one of the world's worst regions for pirate attacks until recent years when dramatically increased patrols neutralised the high-seas bandits.

But attention has now turned to the issue of illegal migrants, after a series of cases of Afghans and Pakistanis travelling illegally from Malaysia to Indonesia by boat.

Prime Minister Najib Razak admitted for the first time afterwards that illegal migrants are using the country as a transit point.

"We are doing our best. Of course there are syndicates involved in human smuggling," Adnan said, adding that his agency last year caught 416 people for entering and leaving the country illegally.