Malaysian police say that from an Islamic State base in Syria, Muhammad Wanndy Mohamad Jedi has been using social media to recruit Malaysians and plot terrorist attacks.

On his public Facebook page under the name Abu Hamzah al-Fateh, Wanndy ridiculed his listing by the US Treasury's Office of Foreign Assets Control, saying it would only make him more cautious about his movements and communications.

The US says Wanndy is a senior leader of a group of hundreds of Malay-speaking fighters in a unit called Katibah Nusantara who are under Islamic State's control in the Middle East.

Last month Foreign Minister Julie Bishop warned that an estimated 600 fighters from south-east Asia could return after surviving the campaign against IS in Syria and Iraq and establish an Islamic caliphate in the southern Philippines, "bringing the threat right to our doorstep".

Philippine President Rodrigo Duterte has ordered his troops to step up attacks on the Abu Sayyaf terrorist group whose leaders have sworn loyalty to IS, declaring his government "will go ahead and kill them to the last man".

Philippine armed forces' Chief of Staff Eduardo Ano said on Monday his troops could eliminate Abu Sayyaf within months.

"They are no match for us," he said.

But with fast boats, millions of dollars in ransom payments from the families of kidnap victims and support from sympathetic locals and corrupt officials Abu Sayyaf factions have survived many military offensives over more than a decade.

In 2014 the United States ended a US military program to train Philippine forces to counter the group.

The US government said at the time the Abu Sayyaf had "largely devolved into disorganised groups".

But over the past two years factions of the group have been involved in kidnapping dozens of people, attacked foreign cargo vessels and carried out several deadly attacks, including in a night market in Davao, the Mindanao city where Mr Duterte made his name as a crime-fighting mayor.

In January, Abu Sayyaf militants beheaded a 70-year-old German sailor and last year beheaded two Canadians.

Counter-terrorism expert Sidney Jones believes the likelihood of a caliphate emerging on Australia's doorstep is low but he said the more likely danger is that pro-IS extremists with deadly skills may use bases in the southern Philippines to plan hits in Mindanao and Manila, or train operatives to carry out attacks elsewhere in the region.

"It is unlikely that hundreds of foreign fighters will flee there as Islamic State is pushed back but even a dozen could cause serious damage," Ms Jones wrote in a paper published in March by the Lowy Institute.

Ms Jones said that an alliance of pro-Islamic State groups in the Philippines appears to have a steady stream of funding, apparently arranged in part through Mahmud Ahmad, a Malaysian former professor who has joined Abu Sayyaf. Mahmud has been on Malaysia's most wanted list since 2014.

Last week Philippine authorities identified a Middle Eastern couple allegedly linked to IS who was planning bomb attacks in the Philippines.

The arrests followed tip-offs from US and Kuwaiti officials.