Seven Indonesian sailors have been taken hostage by gunmen believed to be Abu Sayyaf terrorists in the Sulu Sea, in the fourth such abduction in recent months.
The latest incident occurred on Monday - the same day that Indonesia, Malaysia and the Philippines agreed to designate a transit corridor for commercial vessels in the seas between Sabah, the southern Philippines and Indonesia's Sulawesi Island, in a move aimed at curbing abductions.
The incident is the third involving Indonesian crewmen.
The militants abducted 10 Indonesian sailors on March 29 and another four on April 15. All were released last month.
Notorious for kidnapping people to extort millions of dollars in ransom, the Abu Sayyaf in April abducted a group of Malaysian sailors in the same waters, releasing them early this month.
The organisation was formed by disgruntled Moro Islamic fighters in 1991 with funding from Al-Qaeda. It has now pledged allegiance to the Islamic State in Iraq and Syria terrorist group.
Meanwhile, the militants have released a Filipina who was abducted nine months ago along with three foreigners from a resort in the southern Philippines.
Jakarta: No coal for Manila yet
JAKARTA • Indonesia yesterday decided to extend a moratorium on coal shipments to the Philippines, saying the move will remain in place until Manila can secure its waters.
"The moratorium on coal exports to the Philippines will be extended until there is a guarantee for security from the Philippine government," Indonesian Foreign Minister Retno Marsudi told reporters.
Indonesia supplies 70 per cent of the Philippines' coal import needs, which Indonesian data shows stood at about 15 million tonnes, worth around US$800 million (S$1.08 billion), last year.
Indonesia's transport ministry has issued a notice informing all harbour masters they were "strictly prohibited from issuing permits to all Indonesian-flagged vessels bound for the Philippines, without exception".
To prevent any commercial vessels from breaching the ban, Indonesia will also ramp up patrols in its waters bordering the southern Philippines, the transport ministry's water transport director-general A. Tonny Budiono said in a statement.
It is not yet clear how significantly trade will be affected by the ban, but it could severely disrupt the flow of goods from Southeast Asia's largest economy to the Philippines.
The Sulu and Celebes seas form a key waterway between Indonesia, the Philippines and Malaysia, and are used for the passage of 55 million tonnes of goods and more than 18 million people a year.
REUTERS, AGENCE FRANCE-PRESSE
In Monday's incident, the Indonesians kidnapped were part of a crew of 13 manning the tugboat Charles 001, which was towing a barge.
The kidnapping was carried out by two different groups of gunmen in two phases, at 11.30am and 12.45pm local time, Indonesian Foreign Minister Retno Marsudi told reporters.
"After carrying out intensive communication, coordination and verification with a number of parties, from Indonesia and the Philippines, we received confirmation on the evening of June 23 that Indonesian sailors had been taken hostage," she said.
Six other crew members had been released, along with their tugboat and barge, she said.
"The Indonesian government strongly condemns the repeat of abduction of Indonesians by armed groups in the southern Philippines. This third incident cannot be tolerated," she added.
The Indonesian government will explore all possible ways to rescue the hostages, and call on the Philippine government to ensure security in the waters around the southern Philippines so that economic activities are not affected.
Meanwhile, Senior Superintendent Wilfredo Cayat, the Sulu provincial chief, said yesterday that the Abu Sayyaf released Ms Maritess Flor, 41, late on Thursday.
She was abducted along with two Canadians - Mr Robert Hall, 51, and Mr John Ridsdel, 68 - and a Norwegian, Mr Kjartan Sekkingstad, 57, on Sept 21 from a resort in Davao province and taken to Sulu.
Mr Hall and Mr Ridsdel were both executed by the extremists. Mr Sekkingstad's fate remains unknown.
After meeting Ms Flor yesterday, Philippine President-elect Rodrigo Duterte said the time would come when he would have to confront the militants. "There will be a time that I will have to confront the Abu Sayyaf," he said. "The kidnapping must stop."