Australian PM says man who allegedly tried to bomb rally deserves 'full force of law'

Police should "throw the book" at a man who allegedly lobbed a homemade bomb into a crowd at a rally in support of Indigenous Australians, Prime Minister Anthony Albanese has said.

The 31-year-old man was detained after hurling an item into a throng of around 2,500 people who had gathered in Perth to mark Australia Day, police said.

While many across Australia celebrated the country's national day on Monday, many Indigenous Australians and their advocates held "Invasion Day" rallies to commemorate the cultural destruction of Indigenous communities under European settlers.

Police said the device did not detonate and no injuries were reported.

Speaking to reporters on Tuesday, Albanese said the the incident was "quite shocking", but added that he could not comment any further as "the matter is now before the courts".

"I look forward to him being prosecuted to the full force of the law," he added.

The man - whose identity is suppressed by a court order - is charged with making explosives and intending to do harm, but police are investigating whether he can also be charged with terrorism offences.

Authorities say the object thrown was "a homemade improvised explosive device" containing a mixture of potentially explosive chemicals, nails and metal ball bearings.

In a subsequent search of the man's home, police said they found a "combination of chemicals and materials consistent with the manufacture of homemade explosives".

Western Australia's Police Commissioner Col Blanch said the incident was being treated as a "hostile act" but added police are investigating whether there was political, religious or ideological motive to the alleged attack - a requirement for terror charges.

The alleged bomb incident comes during a time of heightened sensitivity for Australians, after 15 people were killed in a shooting last December at a Jewish festival on Sydney's Bondi Beach.

After the incident at the Perth rally, West Australian Premier Roger Cook said "we can't let hate win".

"Now, more than ever, it is important that we treat each other's views with respect," he said. "It's our differences and diversity which has made Australia the country that we all love."

The man has been remanded in custody and will appear in court again on 17 February.