There have been no fatal mass shootings in the 20 years since Australia introduced tough gun laws and the overall rate in firearm killings has declined, a study has shown.

Key points: Researchers say evidence of no mass shootings since Port Arthur proves Howard's gun laws worked

Mass shooting is defined as four or more people shot in one incident

US gun control advocates using Australia as example

The research, published today in the Journal of the American Medical Association, examined firearm violence in Australia since the introduction of John Howard's ban on semi-automatic weapons after the 1996 Port Arthur massacre.

Professor Simon Chapman, public health expert at Sydney University Emeritus and the lead researcher on the project, said they now had hard evidence to show the repercussions from strict gun control laws.

"If you take away the means of committing a mass killing with firearms, you don't have mass killings for the next 20 years," he said.

"That's been our experience here [Australia]."

A mass shooting is defined as four or more people shot in one incident.

In the 18 years prior to Port Arthur, Australia experienced 13 fatal mass shootings in which 104 victims were killed.

In the United States over the past 1,266 days, there have been 1,000 mass shootings, with the most recent being the Pulse Nightclub shootings in Orlando.

Professor Chapman said the evidence showed the Australian legislation had been successful.

"Twenty years since the National Fire Arms Agreement, which John Howard brokered in 1996; we all remember why he did that, it was to try and stop or reduce the likelihood that there be any more massacres, and that's happened," he said.

"People shooting people and their families, their neighbours, their associates, gang members, that sort of thing — all of that is down as well."

US gun control advocates say Australia is a good example

Gun control advocates in the US, including likely Democratic presidential candidate Hillary Clinton, have cited Australia as a good example for gun reform.

"They [Australia] were able to curtail the supply and to set a different standard for gun purchases," Mrs Clinton said.

Professor Chapman said it could be difficult for Australians to understand why the US had struggled to push through law reform that would make it tougher for citizens to get their hands on guns, considering the rates of firearm violence there.

"Evidence can take you so far, and thankfully in Australia evidence was taken on board," he said.

"But over in the United States you've got such widespread fear and ideology so ingrained in that society."

The US Senate recently rejected four proposals that would have tightened gun laws.

A group of eight Democrat and Republican senators followed up by presenting a bipartisan proposal to the US Senate that they begged their colleagues to pass.

Currently a group of Democrats, who have been pushing for action on gun control, have shut down the House of Representatives to protest against their chamber's lack of action.

Professor Chapman said Australians had a lot to thank their politicians for when it came to the country's gun laws.

"That shows what can happen by sensible legislation. I think Australia's an example for the rest of the world here," he said.