There has been a dramatic rise in the number of registered guns across New South Wales, with the biggest rises in gun ownership in Sydney's most affluent suburbs, including Neutral Bay, Pyrmont and Sydney's CBD.

The latest figures obtained by the NSW Greens show there are now more than 850,000 firearms in private hands, which equates to one gun for every nine people. That is an almost 40 per cent rise since 2001.

NSW Greens MP David Shoebridge said he was so concerned about the surge that his party is going to introduce legislation that will attempt to impose limits on the number of firearms people can register.

"When you live in metropolitan parts of the state, we need a reasonable cap on the number of guns," he said.

"Why should anyone have more than two or three or at most five guns if they live in the middle of metropolitan Sydney?

"That's what politicians are refusing to grasp, that most people want a cap on the number of guns that their neighbours can own."

In 22 of the state's 600 postcodes, registered guns now outnumber people.

Senator Shoebridge said that was concerning.

"The sheer number of guns in fairly ordinary metropolitan parts of Sydney really shocks people," he said.

Figures obtained by the Greens under freedom of information (FOI) laws shows Liverpool has the highest number of registered guns in the Greater Sydney region, with 4,689.

Chester Hill is next with 4,505, followed by Horsley Park and then Bexley with 4,239 and Bankstown with 2,200.

Senator Shoebridge said he did not think the Greens' gun legislation would be passed.

"But we don't pretend that that will get through Parliament because we know that both the Labor Party and the Liberal Party are scared of the gun lobby and they are refusing to take the steps to even put some teeth in John Howard's firearm laws, and that's what we need now," he said.

"They were good laws when they were passed but there is loophole after loophole being found in them and we need to be closing those loopholes."

While Senator Shoebridge does not yet have the support of other parties, he does have support from Stephen Blanks, the president of the New South Wales Council of Civil Liberties.

"The Council of Civil Liberties has never been supportive of a right to bear arms or to own as many guns as a person wishes," he said.

"You have to take into account the community interest in safety and there is a very, very strong, overwhelming interest in the community to be safe from gun crime, inappropriate gun use and the risk of guns being stolen and used illegally."

Gun owners say a diverse range of people enjoy shooting

The Greens' plan to introduce legislation limiting the number of guns a person can own has outraged gun enthusiasts.

"It's not all rednecks [using guns]. You've got doctors, you've got nurses, you've got barristers. It's across the board," said Kym McEwen, the secretary of the central coast branch of the Shooters and Fishers Party and secretary of the NSW Sporting and Recreation Club.

As the owner of 12 registered firearms, he was not surprised to see that the number of registered guns had gone up across NSW.

"Last weekend I was out at Bathurst helping a farmer eradicate some foxes and I was there with a doctor, I was there with a mechanic, I was there with two police officers and I was there myself," he said.

"So it's a wide variety of people that get into the shooting."

In a statement, New South Wales Police said all firearms licence holders are subject to a range of criminal and suitability checks.

They add that each firearm acquisition has to have a permit, and a good reason is required for each and every additional weapon.

NSW Police attribute the increase in the number of licences in part to the increase of club memberships for the sport of target shooting and recreational hunting.

John Piper, a member of the Newcastle Lake Macquarie Clay Target Club and the Sports Shooters Association of Australia, owns nine guns and said any attempt to put a limit on the number of guns he can register is ridiculous.

"It's a lack of understanding as to why you need to own more than one or two guns," he said.

"I'm involved in two major areas of firearm usage, which is hunting and clay target shooting, and one gun doesn't cut it.

"Like the racing car analogy: rally racing versus touring cars versus hill climb versus quarter mile drag - you just can't use one vehicle for all three or four of those areas."