Australian counterterrorism officials fear local Islamic State supporters will be energised by a new speech believed to be by the group's reclusive leader Abu Bakr al-Baghdadi.
- Speech urges the heavily weakened militant group to fight to the death in Syria and Iraq
- Baghdadi's message to militants was that he was alive and well
- US intelligence officials are still working to verify the recording
The audio recording was released online by the militant group overnight, fuelling US suspicions the IS leader has been in hiding on the Iraq-Syria border and not dead, casting further doubt on claims by Russia it had killed him in an air strike in May.
In the rambling 46-minute recording the speaker, who sounds like Baghdadi, appears to refer to recent events, including North Korean nuclear threats to the US and Japan, as well as the "nearly year-long battle for Mosul", which fell to Iraqi forces in July.
Senior Australian counterterrorism officials told the ABC they feared the speech would be a morale boost for local supporters who have been demoralised by Islamic State's retreat in Syria and Iraq.
One official said any new speech by Abu Bakr al-Baghddi was a "massive" concern.
Security analyst Thomas Sanderson, from the United States Centre for Strategic and International Studies, said Baghdadi's message to militants was that he was "alive, well, relevant and perhaps lethal".
"Certainly it would motivate young men and some women to now act on this, where they feel that their leader is alive, that the cause is still alive," he said.
"And that therefore this would be a good time to mark that development with a strike of some sort.
"The change that it is does suggest here is that other fighters will be stimulated by this, and they will have a boost in their morale and you could have a boost in recruitment."
US intelligence officials are still working to verify the recording but reportedly believe the speaker is Baghdadi and that it was recorded as recently as August.
Speech 'will provide a rallying point'
Former Australian Defence Department senior executive Jacinta Carroll, from the Australian Strategic Policy Institute, said a recent alleged IS plot to smuggle a bomb onto a plane suggested senior terrorists in Syria and Iraq had a direct line to supporters in Australia.
"The concern now is that we are seeing this type of direction happening, we saw the technical capabilities being provided by ISIS-aligned groups to enable the Sydney aviation plot that was disrupted," she said.
"And we're seeing funds, plans and some people going into places like the Philippines to make attacks occur.
"The impact of hearing Baghdadi's voice is that it appears that this very embattled group still has their leader and he provides some rallying point.
"It likely will not change the current threat level for Australia, it probably won't in and of itself cause people to mount a particular attack.
"But it will provide a continued rallying point to do things in the name of this group."
The speech appears to give little instruction to IS militants, but urges them to fight to the death in Syria, calling on supporters around the world to attack "information centres", an apparent reference to the media.
Professor Greg Barton, a terrorism expert at Melbourne's Deakin University, said the speech appeared to be primarily focused on local fighters in Syria.
"It seems designed to inspire remaining fighters in areas outside Raqqa to fight to the death," he said.
"He makes a point to emphasise that they don't give up without firing their last weapon and do it in blood."