Indonesia's handling of a recent spate of hijackings of coal-laden tugboats and the kidnap of their crews could determine whether the country's already serious problem with piracy spirals into a situation akin to that seen off the coast of East Africa in recent years, according to a maritime security expert.

The hijack of towing vessel TB Henry and capture of its four crewmembers off the southern coast of the Philippines by suspected members of the Islamic extremist network Abu Sayaff last Friday was the third such act of piracy in the Sulu Sea in the space of two weeks.

The militants, who are based in the southern Philippines and have previously pledged allegiance to Islamic State, are reportedly demanding 50 million Filipino pesos ($1.1 million) to free the Indonesians among up to 18 kidnapped crewmembers they are holding.

According to Peter King, a former Royal Marine Commando who founded maritime security consultancy firm the International Maritime Anti-Piracy Advisory Group, should their demands be met, it could trigger an explosion in hostage-focused piracy in the region like that seen off the coast of East Africa in previous years.

"If these ransom demands are met, we could see the floodgates open," he told VICE News. "As we saw in Somalia, as soon as insurance companies paid out for the first few, land-based Somalis responded and the whole situation grew."

King's comments followed the suggestion on Thursday by Indonesian chief security minister Luhut Pandjaitan that piracy on the country's sea border with the Philippines could see it become "a new Somalia," though hijackings in the Sulu Sea, where the territorial waters of Indonesia, Malaysia, and the Philippines meet, have so far not approached a comparable scale or nature.

An estimated $40 billion worth of cargo transits through the Sulu Sea each year, much of it transported aboard supertankers that cannot negotiate the crowded waters of the Malacca Straight between Indonesia and Malaysia, which is already a major hotbed of piracy. While such supertankers have been targeted by Somali pirates in recent years, so far hijackings in Southeast Asia have mainly affected smaller vessels.

"This has been more of a theft issue," said King, pointing out that in most cases the pirates simply sought to steal oil being transported on smaller tankers before escaping.

In the wake of the recent hijackings, Pandjaitan said the foreign ministers of Indonesia, Malaysia, and the Philippines will meet to discuss the possibility of joint patrols, and the armed forces chiefs of the three countries are set to hold talks in Indonesia's capital Jakarta on May 3.

Piracy near Somalia's coast has subsided in the last few years, mainly due to shipping firms hiring heavily armed private security details and increased patrols from international warships. Gains have also been made to combat hijackings off the coast of West Africa — which in 2014 was reported to be the world's new piracy danger zone — leaving the waters off the coast of Indonesia to emerge as the global hub of piracy, amid a general growth in the activity in Southeast Asia.

According to Allianz's annual Safety and Shipping Review 2016, Southeast Asia now accounts for around 60 percent of global piracy incidents, while Indonesia is "the top global hotspot" for the crime.

Meanwhile, the Far East Asia region saw the biggest year-over-year increase in incidents, with a 288 percent growth in numbers of hijackings largely a result of a surge in incidents off the coast of Vietnam from seven in 2014 to 27 last year.

But Sam Bateman, a professorial research fellow at the Australian National Centre for Ocean Resources and Security at the University of Wollongong, has urged caution on drawing close comparisons between the piracy currently being perpetrated in Southeast Asia and that previously seen off the coast of Somalia.

In an article published this month by the Asia & the Pacific Policy Society, Bateman points out that the hit-and-run nature of the piracy seen in Southeast Asia is much different to that seen off the coast of Somalia, where violent hijackings of enormous vessels saw entire crews held for weeks or months while ransom negotiations were undertaken.

"Absolute numbers of attacks give a misleading impression of the situation," wrote Bateman. "While piracy and sea robbery remain problems in parts of Asia, the threat should be kept in perspective. Most ships transiting regional waters are not at risk unless they slow down or anchor in areas where attacks occur."

Though the recent attacks in the Sulu Sea by Abu Sayyaf have seen crewmembers kidnapped and payment demanded for their release, the tugboats they have targeted and number of people captured remain incomparable to the scale of incidents seen off the coast of East Africa.

King is keen to point out that, while bowing to the ransom demands could encourage more criminality in Southeast Asian waters, an important difference between the region and Somalia is the lawlessness seen in the East African nation. While the governments of Southeast Asia have struggled to deal with the theft-focused hijackings of smaller vessels currently afflicting the region, he says they are far more capable of collaborating to effectively respond to supertankers being commandeered and held for ransom.

"[In Somalia] you could pretty much do what you wanted, whether it was on land or off shore, pirates could pretty much do what they wanted," he said. "It certainly seems to be much better patrolled in [Indonesia]."

In response to the recent incidents, the Indonesian Navy has instructed all commercial vessels "to avoid piracy-prone waters around the southern Philippines," a spokesman for the Indonesian military said.

The navy is increasing patrols around Indonesia's borders with Malaysia and the Philippines "to prevent acts of piracy and hijacking," Tatang Sulaiman told Reuters.

The Kuala Lumpur-based Piracy Reporting Centre has also warned ships sailing in the Celebes Sea, which sits south of the Sulu Sea, and northeast of the Malaysian state of Sabah on the island of Borneo to stay clear of suspicious small vessels.

Meanwhile, two Indonesian coal ports have blocked departures of ships for the Philippines and more suspensions are expected, said Pandu Sjahrir, chairman of the Indonesian Coal Mining Association, and a director of Indonesian coal producer Toba Bara Sejahtera. Toba had suspended all shipments to the Philippines, Sjahrir said. Other companies had canceled shipments "from both sides," he added.

Indonesian state-owned coal miner Bukit Asam said it was diverting Philippine coal shipments to Hong Kong for the next three months.

Indonesia, the world's largest thermal coal exporter, supplies 70 percent of the Philippines' coal import needs, which Indonesian data shows stood at about 15 million tons, worth around $800 million, last year.

Philippine coal importers, however, said they could import coal from other countries including Australia, South Africa, and Russia and source more locally if Indonesian shipments dried up.

Follow Charles Parkinson on Twitter: @charlesparkinsn