The neighbours had already launched joint sea patrols four months ago in the same area, the Sulu Sea.

Fears have been growing that the Islamic State (IS) group is trying to establish a Southeast Asian outpost in the southern Philippines after gunmen waving the jihadists’ black flag occupied the Muslim city of Marawi in May.

They have fought off a US-backed military assault for almost five months and the conflict has left hundreds dead.

There have also been a spate of kidnappings in the Sulu Sea by the Abu Sayyaf, a Philippine Islamist militant group.

A ceremony to announce the patrols was held Thursday at the Subang air force base outside Kuala Lumpur and was attended by defence ministers from the three countries.

A Malaysian defence ministry spokeswoman said the patrols were aimed at combating the threat from “Daesh (IS), piracy and sea robberies”.

The countries will take turns to lead the patrols, with Malaysia starting in November, followed by the Philippines in December and Indonesia in January.

In a speech at the ceremony, Malaysian Defence Minister Hishammuddin Hussein said some US$40 billion (RM169 billion) in trade passed through the Sulu Sea every year and no single country could police the waters alone.