Australia's main domestic security agency on Tuesday raised the terrorist threat level against police from "medium" to "high" in response to recent international attacks targeting officers.

The threat against police as assessed by the Australian Security Intelligence Organization now equals the threat to the wider Australian community which was lifted to "high" in September last year, Australian Federal Police said in a statement. "High" is the second highest level on a scale of four.

"Recent events in France, Canada and Australia serve as a sobering reminder of the risks associated with policing," the statement said.

A gunman is suspected of killing a Paris police officer this month before taking several people hostage in a grocery store. Another two officers were injured while storming the store, leaving the gunman and four hostages dead.

In October, Canada was hit by two terror attacks by so-called "lone wolves" believed to have been inspired by the Islamic State group. In Ottawa, a gunman shot and killed a soldier at Canada's National War Memorial and then stormed Parliament before being gunned down. Two days earlier, a man ran over two soldiers in a parking lot in Quebec, killing one and injuring the other before being shot to death by police.

In the Australian city of Melbourne, two police officers were stabled by a teenager who was later shot dead in violence in September suspected to have been inspired by the Islamic State group. An Islamic State supporter and two of his hostages died when police ended a siege in a Sydney cafe last month.

The police statement said there are an increasing number of Australians inspired by groups such as Islamic State "with the intent and capability to conduct an attack against police."

Queensland state Police Commissioner Ian Stewart said there was no single event that led to the raised alert.

Western Australia state Acting Police Commissioner Stephen Brown urged police in that state to lay their uniforms on their car seats when they're driving to or from work instead of hanging them where they are visible through the car windows.

"We are highly visible; we are easy to target," Brown told reporters. "You simply call us and we come."