The war launched by so-called Islamic State in south-east Asia in recent weeks will be a big problem for Australia for decades, according to a top US military and intelligence figure.

A force of about 500 Daesh fighters took control of the city of Marawi in the Philippines five weeks ago and the Philippines army has failed to retake it, despite fierce daily fighting.

"This is a big concern for you," retired US general and former CIA chief David Petraeus told Fairfax Media.

"This is not a problem that can be resolved in years but in decades, and one where Australia could take the lead," he said. "A point that political leaders have to communicate is that this is a generational struggle.