Australia's number of registered firearms is 25 per cent higher since the Port Arthur massacre in 1996, a report reveals.
More than four million guns are owned by civilians nationwide equating to one for every seven Australians, according to an Australia Institute study published on Wednesday.
A firearms licence holder on average owns more than four guns, with two individuals in suburban Sydney each owning more than 300 firearms alone.
Guns are also widespread in metropolitan and suburban areas, with one in three firearms in NSW located in major cities, according to the report which relies on data from state police annual reports.
The sharp spike in gun ownership and lack of transparency from states and territories about the types of guns are concerning for public safety, Australia Institute research manager Alice Grundy said.
"Australia has a reputation for good firearm regulation in the wake of Port Arthur, but with increases in ownership rates and a lack of consistency and transparency around the country, the policy settings are creating dangerous conditions for the public," she said.
A total of 35 people were killed in the quiet Tasmanian tourist town of Port Arthur in 1996 when Martin Bryant opened fire with multiple, high-powered weapons.
The worst mass killing in modern Australian history prompted then-prime minister John Howard to introduce a buyback scheme and a national firearms agreement including various ownership restrictions.
But information about guns often slips through the cracks because of inconsistencies between state and territory regulations for registering guns, sharing information between police forces keeping records of the type of guns owned.
James Walsh, CEO of the Shooting Industry Foundation Australia, said the public needs a clear distinction between law-abiding gun owners and criminals who possess illegal firearms.
"The issue is the person who has the gun robbing the bank that can't be traced. They're ones who society needs to worry about," he said.
He said a four-to-one ratio of registered guns to gun owners was not concerning as shooters need them for various uses and they are stored safely.
"We deal in legal and regulated guns so that number doesn't worry me."
The 54-page report found most Australians support stricter firearms regulations, with seven in 10 poll respondents saying laws should make it harder to buy a gun.
In addition to the millions of registered guns across the country, a sizeable number of illegal firearms are procured through the black market.
Deakin University criminologist David Bright, who recently published a book on illicit firearms, estimates there are up to 600,000 guns in Australia that cannot be traced to a registered owner.
"Given the history we've had and the sheer numbers of firearms, we should have concerns as citizens," he told AAP.
There should also be better information-sharing between authorities to prevent deadly incidents, Dr Bright added.
As an example, he pointed to the fatal shootings of two Queensland police officers and a neighbour at a semi-rural property at Wieambilla in what was later described as Australia's first fundamentalist Christian terrorist attack.
The report recommends urgent reforms including the development of national firearms register.
