Image caption The recent shootings have been blamed on a dispute involving the Hell's Angels and other gangs

A smouldering feud between motorcycle gangs in Australia is a step away from an all-out war, according to one of the country's most senior former police officers.

In recent weeks there have been multiple shootings in Sydney blamed on the gangs.

Homes have been sprayed with gunshots while children have slept inside, and there have been several related shootings in South Australia, Western Australia and Queensland.

Clive Small, a retired assistant commissioner of New South Wales, said they were part of a fight for control of the amphetamine and weapons trade, as well as competition for new recruits and extortion rackets.

He said that if a truce was not put in place soon, then the power struggle could intensify into a far more bloody conflict.

"One side will say 'hang on, we've had enough', and they'll negotiate a peace deal," Mr Small explained.

"The other situation is that we could see a loose bullet being fired into a house and hitting the family of a bikie member, particularly if it was a child.

"I think that would push it over the brink and then we'd be looking at a more substantial escalation of the situation, perhaps even a war."

'Growing menace'

It is estimated there are 35 "outlaw" motorcycle groups in Australia with 3,500 "patched" or official members. Since the 1980s there have been about 100 biker killings across the country and 1,000 shootings.

Image caption Mr Small said biker gangs constituted a growing threat

The epicentre of the current outbreak of violence is Sydney, where there have been more than 60 drive-by shootings so far this year.

Detectives mostly blame them on a dispute between the Hells Angels and the Nomads.

Clive Small charts the tensions back to the infamous Milperra massacre in 1984, when six bikers were shot dead in a pub car park in Sydney, while a teenage girl was killed in the crossfire.

Since then, he said, the motorcycle gangs had "really grown as a menace". Traditional criminal codes where families were never targeted had been abandoned by "nasty, violent people."

In 2009, members of the Commancheros clashed with Hells Angels at Sydney Airport, where one man was beaten and stabbed to death in front of dozens of horrified passengers.

"They (gang members) do look hard but they are generally family men - but you wouldn't want to cross them," said Macca, a long-time resident of Sydney's Kings Cross district, a hub of the city's illicit drug industry.

"They can be really dangerous. I seen a bloke get axed across the back of the neck. He died. Seen a couple of blokes get chopped up (with knives) and left in dumpsters."

'Clear message'

The authorities have put some measures in place to try to curb the violence. New laws have made it illegal to wear certain biker "patches" or insignia in Kings Cross.

And New South Wales state premier Barry O'Farrell says the gangs must not be allowed to act with impunity.

Image caption Randall "Animal" Nelson said gangs were being blamed for criminal violence

"This is about sending a clear message that… wearing bikie colours doesn't make you a superhero that protects you from the long arm of the law," he said.

"Equally, this is about… giving the police the tools they need to tackle the shooting spree that's affecting our city."

Several Australian states have also introduced legislation that would criminalise membership and association with biker gangs, although previous attempts have been struck down by the High Court.

But Randall "Animal" Nelson, a founding member of the Kings Cross Bikers Social and Welfare Club, which does charity work for people with disabilities, hospital patients and prisoners, believes the bikers are being unfairly castigated for the spate of shootings in Sydney.

"Propaganda is a big thing," he said. "Whatever the police say, the people believe. Most media have blown it out of proportion."

"All they want to hear is blood and guts. They don't hear the good things bikers do. Thousands of bikers do thousands of things for thousands of people."

He said criminal elements with no biker affiliations were to blame and that gang members were being victimised because of their reputation and distinctive clothing.

But author Ross Coulthart believes outlaw gangs in Australia are responsible for an increasingly brutal fight over multi-million dollar drug rackets.

"These battles are nothing new," he said of the recent violence in Sydney.

"(But) what is disturbing about what is happening now is previously if a bikie had a gripe with a bikie, it would be two blokes with guns and one would come away dead or with holes in him."

"The phenomenon now is for people to get a machine gun and spray the front of a house," he said.