A federal politician says New South Wales police have behaved like “bastards” while dealing with soccer fans, who have a long-running and sometimes violent relationship with officers.

Liberal Democrat senator David Leyonhjelm made the comments after a so-called “nanny state” Senate committee – where the police’s handling of Western Sydney Wanderers’ A-League supporters was being probed.

“Now there’s a saying, ‘ACAB: All Coppers Are Bastards’. Cops have earned that. They’ve got to unearn it,” Mr Leyonhjelm said on Tuesday.

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Fans of the Wanderers have had a series of clashes with police throughout the club’s three-year history, as authorities tried to stamp out anti-social behaviour from a minority of supporters. 

However, attempts at collaboration between police and supporters have failed to settle tensions, with fans continuing to be banned and evicted from games.

Fans claim police are heavy-handed and overzealous with large sections of supporters when only a few of them behave poorly.

Tensions escalated again on Wednesday when Police Association NSW (PANSW) released a statement condemning Mr Leyonhjelm’s comments and demanding Prime Minister Malcolm Turnbull make him step down from a committee into law enforcement.

“The Senator by repeating those comments and backing them up is not acting how any elected official should behave,” PANSW president Scott Weber said.

“Such attitudes and vitriol are, and always will be, an affront to community decency and values.

“Fringe dwellers should have no platform to promote and extend their extremist views.

“Especially at a time when police officers are themselves under the most serious threat levels in our history.”

Mr Weber’s statement also referred to football fans as “grubs” twice.

“Anyone who thinks what has been happening at Western Sydney Wanderers games, and in the hours before them, is not dangerous needs to take a long hard look at themselves. Police are there to protect everyone – even these grubs.”

The statement did nothing to diffuse Mr Leyonhjelm’s use of the controversial term on Wednesday.

And they wonder why the fans call them bastards. https://t.co/GxFnZnVu3a

— David Leyonhjelm (@DavidLeyonhjelm) November 4, 2015

My advice to Ray Hadley and anyone concerned about being called a bastard, including coppers, is don’t be a bastard.

— David Leyonhjelm (@DavidLeyonhjelm) November 4, 2015

He told News Corp that police had their approach to football fans completely wrong, with an “anti-wog attitude”.

“Look at my surname, you could say I’m of ‘wog’ extraction,” Mr Leyonhjelm said. “And frankly this is an anti-wog attitude.

“It’s a police attitude coming from the top that Wanderers fans are dodgy, and that only heavy-handed policing will bring that under control.”

Mr Leyonhjelm is on the committee flanked by Labor senator Sam Dastyari, who joined the Liberal democrat and the WSW (fans and officials) in dismissing the police’s conduct toward them as dismissive.

The WSW supporter group, the Red and Black Bloc (RBB), along with many other A-League groups, have long been dismayed at the way they are handled by police.

Speaking at the Economic References Committee on Tuesday, NSW Assistant Commissioner Dennis Clifford linked behaviour of WSW fans to the Cronulla riots, according to Mr Leyonhjelm’s chief of staff who was at the hearing.

“Sometimes it’s a handful and sometimes a hundred, causing big disruption and putting lives at risk,” he said. “I don’t agree that we are treating everyone as bad,” Assistant Commissioner Clifford said.

“The lighting of flares is the most dangerous activity I’ve seen on the marches and at games,” he said. “It’s only a matter of time before someone is killed.”

Football fans, particularly those called “active supporters”, conduct themselves quite differently to NRL or AFL fans. 

They conduct marches to games, stand, chant and move around during the 90-minute matches.

Police and stadium managers have long struggled to deal with these supporters, particularly now that no A-League club plays at grounds they own.