The Indonesian Transport Ministry banned ships from sailing to the Philippines after a series of kidnappings worsened maritime safety concerns.
Earlier this week, the government confirmed the abduction of seven Indonesian sailors at gunpoint by an unidentified group in Sulu. This was the third incident of sailors being kidnapped off Philippines by the Abu Sayyaf militants in the south of the country.
The Transport Ministry issued a notice in response to the latest kidnapping and told all harbour masters that they were "strictly prohibited from issuing permits to all Indonesian-flagged vessels bound for the Philippines, without exception".
"This hijacking issue is a serious matter and cannot be tolerated anymore," the ministry's water transport director-general A. Tonny Budiono told AFP.
Budiono also said that Indonesia will have marine patrols in its waters bordering the southern Philippines to ensure that no commercial ships are sailing there.
The Sulu and Celebes Sea are the key waterway between Indonesia, Philippines, and Malaysia. Hence this ban might affect the trade and the flow of goods from South-east Asia's largest economy to the Philippines.
Last month, all these three countries agreed to launch a coordinated patrol in the waterway to control the kidnapping. But another kidnapping happened when the Indonesian sailors were sailing with a coal freight ship.
Sulu is a known shelter of Abu Sayyaf Islamic militants, who have earned millions of dollars in recent years from kidnappings.
The Abu Sayyaf group kidnapped 14 Indonesian sailors earlier this year but later released them.