SYDNEY • Australia yesterday offered to help train the Philippine military to tackle Islamic militants terrorising parts of the country, calling the threat "deeply concerning".

Philippine forces have been besieging militants in the southern city of Marawi for almost 100 days. But the gunmen, flying the Islamic State in Iraq and Syria (ISIS) group's black flag, have defied military assaults including air strikes.

Canberra, which has an extensive defence cooperation programme with Manila, has already deployed two high-tech AP-3C Orion aircraft for surveillance, and is keen to provide further help.

Australia's Foreign Minister Julie Bishop said she recently spoke to Philippine President Rodrigo Duterte. "We would be ready to support the Philippines in the same way we are supporting Iraq in advising, assisting and training," she said. "I went through with the President in some detail the support we have given in Iraq, that does not include troops on the ground. That is advising and assisting."

Australia is part of the coalition fighting ISIS in the Middle East, with 780 defence personnel based in the region.

Ms Bishop said it was "deeply concerning" for the entire Asian region that ISIS has a presence in the southern Philippines, with the United States, Malaysia and Indonesia also offering support.

Mr Duterte declared martial law across Mindanao island, home to 20 million people, on May 23, immediately after fighters flying the ISIS flag rampaged through Marawi.

Their assault on the city ignited an unprecedented urban war.

AGENCE FRANCE-PRESSE