SYDNEY (AFP) - Top US and Australian officials warned on Monday (June 5) that battle-hardened and angry foreign fighters may return to South-east Asia from the Middle East and take up arms in their own countries.

The warning follows the weekend terror attacks in London, which were claimed by the Islamic State in Iraq and Syria (ISIS) group, and comes amid a growing extremist threat in the Philippines.

ISIS fighters will "come back with battlefield skills, they'll come back with hardened ideology, they'll come back angry, frustrated, and we need to be very aware of that," Australian Defence Minister Marise Payne said.

She was speaking at an Australia-US ministerial summit also attended by Pentagon chief James Mattis, US Secretary of State Rex Tillerson and his Australian counterpart Julie Bishop.

Reacting to the London attacks, Mattis said: "We are united... in our resolve, even against an enemy that thinks by hurting us, they can scare us. Well, we don't scare."

US President Donald Trump has instructed the Pentagon to "annihilate" ISIS to try to prevent foreign fighters from escaping and returning home as they lose ground in Iraq and Syria.

The aim is to encircle and kill as many extremists as possible in place, rather than letting them exit a city and targeting them as they flee. This reflects an increasing urgent attempt to stop the fighters bringing their military expertise and ideology back to the West.

"Before, we were shelling them from one town to another," Mattis said.

"We now take the time... to make certain that foreign fighters do not stay to return to Paris, France, to Australia, to wherever they came from, and bring their message of hatred and their skills back to those places and attack innocent people." The issue of countering terrorism was high on the agenda at Monday's annual talks.

Australian officials say they have prevented 12 terror attacks on home soil since 2014 with more than 60 people charged.

In the Philippines, hundreds of civilians are trapped by fighting between the military and Islamist militants who have overrun the city of Marawi on the restive southern island of Mindanao.

Separately, Tillerson said a decision on whether to send additional troops to try to stabilise the security crisis in Afghanistan was still under review.