Jakarta: Seven Indonesians believed to have been kidnapped by the notorious Abu Sayyaf militant group are being kept as hostages after they were ambushed in the Sulu Sea in the Southern Philippines on Thursday.
The Indonesian government has moved to impose a moratorium on the shipment of coal to the Philippines until security can be guaranteed by the Philippines.
Foreign Minister Retno Marsudi strongly condemned the repeated hostage taking - this is the third time Indonesians have been captured by militants this year.
"More than 90 per cent of the coal demanded by the southern Philippines depends on imports from Indonesia," Ms Retno said.
"Therefore a moratorium will continue until the Philippines government provides a security guarantee."
Two armed groups ambushed two vessels - tugboat Charles and coal-carrying barge Robby - on June 23 at 11.30am and 12.45pm local time, seizing 13 Indonesians.
Six have been released and are on their way to Samarinda in East Kalimantan with the two boats but seven remain in hostage. It is still clear how much the kidnappers are demanding in ransom.
Security Minister Luhut Panjaitan has previously expressed concerns Indonesia did not want the popular shipping route in the Sulu Sea to become a "new Somalia".
In May, 14 Indonesians were released by Abu Sayyaf after being kidnapped in two separate incidents.
Abu Sayyaf is a small but brutal militant group known for kidnapping for ransom, which is a main source of funding since its creation in 1991.
Canadians Robert Hall and John Ridsdel, who were kidnapped by the Islamist group in September, were killed after a ransom deadline expired. The Canadian government, like Australia, has a policy of not paying kidnappers.
Abu Sayyaf came out of the separatist insurgency in the southern Philippines, where Muslims represent most of the population unlike the rest of the country, which is mainly Roman Catholic.
Late last year Abu Sayyaf leaders began declaring their support for Islamic State's violent caliphate, sparking fears the remote islands of the southern Philippines would become a haven and training ground for a new wave of Islamic extremists.
A spokesman for the Indonesian foreign ministry, Arrmanatha Nasir, said communication between Indonesia and the Philippines was good and the countries were looking to fast-track joint patrols between Indonesia, the Philippines and Malaysia discussed last month.
