(Adds ICG report)

MANILA, Oct 24 (Reuters) - Islamist militants escaping from crackdowns in Indonesia and Malaysia continue to flee to the Philippines' southern island despite tightening border controls, the head of Manila's counter-terrorism unit said on Friday.

Arturo Lomibao, a former national police chief, said Jemaah Islamiah (JI) members had shown greater "capacity for resilience in the face of successful counter-terrorism efforts against them" and remained a major security threat to the region.

Lomibao said the Philippines and its two closest Southeast Asian neighbours -- Indonesia and Malaysia -- had not fully stopped the movement of militants across their common maritime borders despite the increasing number of arrests in recent years.

"Jihadis associated with Umar Patek continue to arrive intermittently in Mindanao," Lomibao said at a counter-terrorism forum at an army base in Manila, adding the governments in the region must do more to step up border cooperation.

Umar Patek and Dulmatin, both Indonesians, are key suspects in the 2002 Bali bombing that killed more than 200 people. They are believed to be hiding out in the southern Philippines with members of the Abu Sayyaf, a small but one of the deadliest Muslim radical group in the country.

"We need to develop and enhance our counter-terrorism responses and continue to maintain close links with our allies to ensure its adaptability to the terrorist threat at all times," Lomibao said.

Based on intelligence reports, there were nearly 60 militants seeking sanctuary or undergoing training on the southern island of Mindanao, he said.

Lomibao said the government was focusing its efforts to "neutralise" the small but highly mobile unit led by Patek and Dulmatin.

Lomibao said he was also worried about other Islamic militants who "are no longer visible in the intelligence radar screen".

Most of these "missing" militants went to Mindanao four to five years ago to undergo training on guerrilla warfare and in bomb making techniques, he said.

"They may have married locals and could be putting into good use their talents helping our own Muslim rebels in the south," he added.

On Thursday, a leading think-tank said the involvement of foreign militants in the two-month-old fighting between soldiers and rogue members of the Moro Islamic Liberation Front (MILF), the largest Muslim rebel group in the country, could complicate the situation on Mindanao.

"It could serve as a green light to the military to go after the MILF more broadly," the Brussels-based International Crisis Group said in its report: "The Philippines: The collapse of peace on Mindanao". (Reporting by Manny Mogato; Editing by Raju Gopalakrishnan)

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