The Philippines is seeking US and Chinese help to guard a major sea lane as Islamic militants shift attacks to international shipping, officials said Wednesday.

Manila does not want the Sibutu Passage between Malaysia's Sabah state and the southern Philippines to turn into a Somalia-style pirate haven, coast guard officials said.

The deep-water channel, used by 13,000 vessels each year, offers the fastest route between Australia and the manufacturing powerhouses China, Japan and South Korea, they added.

In the past year Abu Sayyaf gunmen from the southern Philippines have boarded ships and kidnapped dozens of crewmen for ransom in waters between Malaysia, Indonesia and the Philippines, raising regional alarm.

Indonesia has warned the region could become the "next Somalia" and the International Maritime Bureau says waters off the southern Philippines are becoming increasingly dangerous.

"If shipowners will skirt that area just to avoid kidnap at sea activities by these terrorists, for sure, it will have an additional cost," Philippine Coast Guard chief Commodore Joel Garcia told AFP.

"It's not just the concern of the Philippines or Indonesia and Malaysia, but of the international shipping community."

Manila plans to ask its longstanding defence ally the United States to hold joint exercises in waters off the southern Philippines to address the problem, Defence Secretary Delfin Lorenzana told AFP on Tuesday.

And Philippine President Rodrigo Duterte last week urged China to launch patrols off the piracy-plagued waters, citing Beijing's dispatch of a naval convoy to the Gulf of Aden in 2009 to protect Chinese ships from Somali pirates.

Duterte made the comments a day after meeting a special envoy from Indonesia who wanted to know what Manila, which has one of the weakest naval forces in the region, plans to do to address the threat.

Garcia said details of the possible sea patrol cooperation with China would likely be discussed at a meeting between the two countries' coast guards in Manila next week.

Lorenzana said Manila plans to "talk to the ministry of defence of China on how to operationalise this joint patrol" off the southern Philippines.

Garcia said rising incidents of piracy around the 29-kilometre-wide (18-mile) Sibutu Passage threaten to push up overall shipping costs, including insurance for vessels, cargo and crew.

Diverting ships to Indonesia's Lombok Strait would be more expensive and voyages would take longer, said Filipino coast guard spokesman Commander Armando Balilo.

The Filipino coast guard recorded 12 piracy or kidnapping incidents in the passage in the last six months alone, on top of four unsuccessful attempts by gunmen to board vessels.

"It (a Somalia-like situation) has not happened, but if it escalates into a full-blown piracy area, that would be scary because they will avoid that route. They will use other routes and shipping costs will rise," Balilo said.