Mr Cerantonio, a convert extremist preacher who has cultivated a significant online following while promoting jihad in the Middle East, was arrested in the Filipino province of Cebu on Friday.

But police intelligence sources say Mr Cerantonio has also recently travelled to the southern region of Mindanao, where the Abu Sayyaf group has waged a violent, decades-long separatist campaign.

An unnamed Philippines intelligence officer was quoted as saying Mr Cerantonio was of interest to Filipino authorities for his domestic terror links.

“This person ... has a website and he propagates extreme teachings and advocates jihad, calling on Muslim brothers to go to Syria and Iraq to fight together with the [Islamic State in the Levant].

“Sometimes he mentions the Philippine government [online] but does not call for violence”.

Police Senior Superintendent Conrad Capa said Mr Cerantonio’s movements and associations were being closely examined.

“We cannot say with certainty that he had any contact with local Muslim groups.”

The top of Mr Cerantonio’s twitter page displays the Black Flag, a symbol commonly used by Islamist groups such as Al-Qaeda and  ISIL, but with the words "Islamic State of Mindanao and Sulu" added in Arabic.

An independent Islamic state ranging across western Mindanao and the Sulu archipelago is the stated goal of Abu Sayyaf, a terrorist organisation that regularly uses kidnappings, extortion, bombings and assassinations to further and finance its aims, and which has been proscribed by the Australian government since 2002.

It has been reported Mr Cerantonio was involved in circulating online a video of hundreds of Muslim Filipino prisoners, including members of Abu Sayyaf.

In the film, the masked prisoners pledge their support for the Islamist fighters in Iraq and Syria, and the Black Flag symbol can be seen behind them.

If Philippine police can establish a link between Mr Cerantonio and Abu Sayyaf, he faces the prospect of charges in Australia under national security and counter-terrorism law.

It is illegal to associate knowingly with members of a terrorist group, provide support or training for a group, raise money on its behalf, or encourage others to join.Terrorist organisation offences carry up to 25 years' jail.

Mr Cerantonio may also face charges in Australia under the Foreign Incursions and Recruitment Act, which outlaws joining, or encouraging others to join, foreign paramilitaries or insurgencies.

Mr Cerantonio has been vociferous in his support for ISIL, the extremist Islamist group waging war in Iraq and Syria.

He remains in police custody in Manila, ahead of possible deportation to Australia. His passport has been cancelled by the Australian government, meaning he is now an illegal alien under Filipino law.

The woman in whose company he was arrested on Friday is in prison in Cebu, facing fraud charges. She and Mr Cerantonio allegedly skipped out on a hotel bill before they found their rented accommodation.

Joean Navarro Montayre told the Cebu Daily News she was married to the Australian-born convert. She said the pair got married three days after they met at the Mactan Shrine in Lapu-Lapu City. The exact nature of their relationship, however, remains unclear.

Ms Montayre also refuted claims Mr Cerantonio was recruiting people to fight for Islam. “As far as I know, he’s good, humble and very intelligent,” she said. “He came here to study our language and Philippine history. The internet is full of garbage, anyone can put accusations there against anyone.”