SYDNEY - POLICE have tightened security around the leader of Australia's most populous state amid fears biker gangs will target him over laws designed to stamp them out, it was reported on Monday.

New South Wales Premier Nathan Rees last week pushed through anti-terror style legislation allowing police to have biker gangs declared illegal in response to escalating violence among rival outlaw motorcycle clubs.

Sydney's Daily Telegraph, citing unnamed police sources, said officers had placed his home under 24-hour guard due to worries the gangs would seek revenge.

Police and the NSW government have refused to discuss security arrangements surrounding the premier.

The report came as police charged a sixth member of the Comancheros gang over a brawl at Sydney Airport last month, when the brother of a Hells Angel was bludgeoned to death in a check-in area.

Under the new laws, police can apply for a motorcycle gang to be declared a criminal organisation by a judge.

Once declared, members found to be associating with one another could be jailed for two years, rising to five years for repeat offences.

Civil libertarians and legal groups say the laws undermine the right to freedom of association and increase the risk of police corruption.

But the NSW government says they are needed to stamp out biker violence and has expressed confidence they can withstand a constitutional challenge.

South Australia state has similar laws and Queensland is in the process of drafting them.

Experts say the biker violence stems from turf wars over drug distribution, particularly crystal methamphetamine or 'ice.' Australia's worst outbreak of biker warfare was in 1984, when six gang members and a teenage girl died in a shootout in a Sydney pub's car park. -- AFP