The head of the Australian Federal Police says there is a direct correlation between inflammatory political discourse and threats against parliamentarians.
AFP Commissioner Krissy Barrett said police regularly saw harassment of MPs increase following periods of heated debate.
"It does have a direct correlation to what we see in terms of threats and abuse, and sometimes it's very immediate," she told Insiders.
Commissioner Barrett said police did not want to curtail free speech or intervene in legitimate political debate, but there was a role for law enforcement when rhetoric escalated into violent threats.
"I would challenge any Australian to read some of these threats and some of the abuse that is reported to us from federal parliamentarians and for anyone to argue that that is free speech or political discourse," she said.
Asked whether One Nation's cartoons depicting politicians being hit by cars were the type of political discourse she was referring to, Commissioner Barrett said they could be.
"We do see examples where there are particular announcements or things like you've just described. There is a reaction amongst the community," she said.
"Words matter, and we do see the flow-on impact from that."
Helen Haines was critically injured in an attack last week. (ABC News: Matt Roberts)
Politicians across the divide have raised concerns about their personal security after independent MP Helen Haines was hit by a car in an attack outside her Wangaratta electorate office last week.
The member for Indi remains in a serious but stable condition in hospital and has had both her legs amputated.
Brendan Nugent, 43, has been arrested and charged in relation to the attack.
Commissioner Barrett said investigators were focused on establishing a motive but cautioned that process could take weeks, even months.
"Sometimes it is difficult to determine a clear motive," she said.
"There is media reporting around his mental health, around some of the social media footprint that is out there in terms of different issues that he may or may not be aligned with.
"We need to work through all of that to determine whether it is directly linked to her role as a federal parliamentarian."
MPs must make own decisions about safety, chief says
Commissioner Barrett said police would continue briefing federal parliamentarians and their staff on security arrangements, but said MPs would need to make their own decisions about their personal safety.
The comments come as some federal members have spoken about fears for their safety, while describing mixed experiences with the security support available to them.
She defended the resources devoted to protecting parliamentarians, arguing the focus should be on how those capabilities are deployed rather than the size of the budget.
"It's about having the flexibility to evolve our capabilities, invest in technology and respond to changing threats," she said.
"At the end of the day we're here to give advice, but I would say it's up to the individual parliamentarian … to make those decisions."
Commissioner Barrett said personal duress alarms were among a range of measures being considered, but stressed that calling Triple Zero was still the most effective option in an emergency.
"I think there is a place for duress alarms, but we need parliamentarians to understand what a duress alarm does and doesn't do."
MPs consider language as parliament returns
Shadow cabinet minister Ted O'Brien said politicians of all stripes would return to Canberra on Monday reflecting on the tone of political debate.
"I think [the attack] demands the nation does pause and think about how we can do things better, and how we can debate better," he said.
"Robust debate is fundamental to our system, but personal nastiness is not. We've got to make sure we can address this."
Ted O'Brien says politicians will be considering the tone of debate in parliament. (ABC News: Ian Cutmore)
Labor frontbencher Catherine King flagged there might be a reassessment of security arrangements at Parliament House, while acknowledging parliamentarians were already "very well looked after" by the AFP.
"Obviously, when an incident … as horrible as this happened to Helen, they'll go back and look at all of the security measures that are in place," she told News 24.
"All our thoughts, I know as we head into parliament, will be with Helen not being there with us."