The Federal Government has confirmed it is investigating a Perth man who apparently supports a militant group believed responsible for mass killings in Iraq.

Junaid Thorne, an Australian citizen who is involved with a group called Millatu Ibrahim Perth, was deported from Saudi Arabia last year after protesting his brother's imprisonment.

His brother was jailed for terrorism offences in the Islamic state but was released earlier this year.

The ABC is not aware of any charges laid against Mr Thorne, who has released a statement saying that he "is not associated with any terrorist groups such as ISIS".

"I do not incite terrorism, or encourage unjustified acts of violence as reported," the statement said.

"If we are to point fingers at a group who fills the position of being a terrorist group, we can include governments such as Australia and America who practice legalised terrorism by oppressing, bombing, and killing our Muslim people and innocent civilians overseas, and also oppressing my Indigenous people at home."

Facebook post praises ISIS 'brothers'

A Facebook post on a page that states it is managed by Mr Thorne and his students praises the fall of Mosul by the Islamic State of Iraq and Syria (ISIS).

The ABC has asked Mr Thorne to confirm this is his page.

ISIS has created chaos in Iraq in recent weeks as they attempt to overrun the government in Baghdad.

"Our brothers in the Islamic State of Iraq and Sham liberate the town of Al Mawssil, and take over the Prison of Tasfeeraat rescuing 600 people from there," one post said.

"May Allah reward them for such a heroic and glorious act. Congratulations to our Ummah this victory and liberation."

Another post criticises a statement from the Australian National Imams Council (ANIC) defending itself from comments it is not doing enough to stop young Australian men from joining armed conflict in Syria.

ANIC issued a statement saying senior members of the Muslim community were working to prevent Australians becoming involved in the conflict, following perceived criticism from NSW counter terrorism squad assistant commissioner Peter Dein.

The Facebook post brands it a "statement of embarrassment".

"The cries and calls for help from our suffering brothers and sisters seem to fall on the deaf ears of our so-called 'Imams' as they continue to abandon their religious duties, replacing it with betrayal and loyalty to their masters from the Kuffar [non-believers]," it says.

Mr Thorne also appears on a separate website in videos of sermons he delivers to small groups on his interpretation of Islam.

Government looking into online posts

Foreign Affairs Minister Julie Bishop today confirmed matters relating to Mr Thorne's online posts were under investigation.

"Any promotion or support for terrorism is against the law in our country," she said.

"And [ISIS] is a proscribed terrorist organisation."

Promoting or engaging with terrorist organisations can be punishable by severe penalties, including up to 25 years imprisonment, she said.

Ms Bishop said the Government had earlier raised concerns about young Australians who were attracted to the conflict in Syria and Iraq.

"We have estimated there are about 150 Australians who have engaged directly in supporting terrorist organisations in Syria, in Iraq or also remaining here in Australia," she said.

"We are taking a range of measures to address what we see as a considerable security risk."