Islamic State has released a tape of its leader galvanising militants, months after he was said to have been killed in a Russian airstrike.

Abu Bakr Al-Baghdadi urged ISIS fighters to wage more attacks in 46 minutes of audio released on Thursday (US time). The date of the tape’s creation and its authenticity have not yet been confirmed.

It is his first purported communication since November last year and comes after numerous reports of his death.

In June, Russia claimed to have killed Baghdadi in a strike near Raqqa in Syria. Senior Islamic State commanders confirmed his death, the Syrian Observatory for Human Rights said in July. The United States raised doubt over the claim.

In the latest audio, Baghdadi alluded to recent attacks on the London Underground and in Barcelona. He also appeared to reference rising tensions between the United States and North Korea.

Baghdadi also alluded to fighting in Mosul, which was recaptured by US-backed Iraqi forces this year. Militants appeared to declare defeat in the city by blowing up the El Nuru mosque in June.

Haroro Ingram, a research fellow specialising in terror propaganda at the Australian National University (ANU), said it was most likely Baghdadi in the audio – and that he was probably not dead.

“For a while there he was getting killed every month. It’s just one of those things where it’s hard to verify,” Dr Ingram told The New Daily.

“How many times have the Russians apparently killed this guy?

“It highlights once again that you’ve got a take with a bit of salt any reports he’s been killed.”

Dr Ingram said the audio was most likely recorded within recent weeks or months.

“Dropping references to current events is part of not only demonstrating that it’s relatively contemporary, but that he’s engaged with what is going on.”

US-backed Iraqi soldiers cheer as they carry a black ISIS flag, with the destroyed Al-Nuri mosque seen in the background, in Mosul. Photo: Getty

He said Baghdadi appeared to be acknowledging the fight ISIS is up against, while also pointing to the “weaknesses” of Western enemies who have been distracted fighting each other.

Dr Ingram said the propaganda was saying of its opposition: “They’re weakening, they’ve got weaknesses, and we’ve got a chance here.

“ISIS has kind of a motto of ‘remaining and expanding’ … This is a theme that it continues to champion in its messaging: ‘Don’t believe what the filthy disbelievers have to say, we remain’.”

The propaganda appeared to be primarily targeted at rallying supporters, but Dr Ingram said ISIS kept in mind its enemies were listening too.

“When you have the leader come out and make a statement, especially how much pressure he’s under, that’s significant in itself.

“It’s very dangerous, even just doing audio like this. Their leadership has been devastated by decapacitating strategies like drone strikes, special operations and war in general.

“They’ve lost several Steve Jobs, in terms of innovative, intelligent men. Their innovative and intelligent men are being killed off and that hurts the group, so having him release this statement is really important. It’s really symbolic for the group.”

The Islamic State has suffered significant losses since Baghdadi’s last communication in November last year.

In the audio, Baghdadi called for attacks on “disbeliever media centres and headquarters of their ideological wars” and “scholars of sin”, according to a translation by SITE.

“Oh Soldiers of the Caliphate, fan the flames of war on your enemies, take it to them and besiege them in every corner, and stand fast and courageous,” Baghdadi said.

“Beware of retreat, or the feeling of defeat, beware of negotiations or surrender. Do not lay down your arms.”

– with AAP