Brunei, Indonesia and Malaysia will open unrestricted air links with the troubled Philippine south while toughening security to stop the movement of terrorists, an official said.

The Philippine island of Mindanao has a notorious reputation as an easy entry point into the country for Muslim separatists and Islamic militants to transport guerrillas and their weapons.

But the three countries yesterday signed a deal with Philippine President Gloria Arroyo on the sidelines of the Asean summit as part of efforts to create a so-called East Asian Growth Area, Arroyo aide Jesus Dureza said.

Flights would connect the islands of Mindanao and Palawan with the three neighbours even though it could "possibly also open it up to what you'd call people who would like to create trouble," he told a news conference.

"The idea of trying to open up our borders for trade and tourism of course necessitates us also hardening our borders ... (to prevent it) from being used also as connectivity for the terrorists," Dureza said.

He said Arroyo signed the deal here with Brunei's Sultan Hassanal Bolkiah, Indonesian President Susilo Bambang Yudhoyono and Malaysian Prime Minister Abdullah Ahmad Badawi "with no limits as to capacity or frequencies".

He said the commitment was effectively for an "open skies" policy involving these destinations.

Filter out the unwanted

Brunei's flag carrier Royal Brunei Airlines has expressed interest in using a Mindanao-Brunei route to service southern-based Filipinos flying to contract jobs in the Middle East, Dureza said.

The leaders agreed to push for the harmonisation of the rules on customs, immigration, quarantine and security procedures to filter out unwanted travellers, he said.

Western intelligence agencies say Jemaah Islamiyah (JI) militants behind the 2002 Bali bombings have set up training camps in Mindanao, the hotbed of a decades-old Muslim separatist rebellion.

Malaysia is meanwhile helping broker peace talks between Manila and the Moro Islamic Liberation Front, the largest separatist group in the area.

The rebel group has rejected allegations by the Philippine military that some of its rogue leaders have sheltered JI militants.