Wanted Syd man 'punched officer in head'

A Sydney man wanted by police after having his parole revoked is back behind bars after allegedly punching an officer in the head.

Plain-clothed officers spotted the 24-year-old and two other men "acting suspiciously" outside a bar in Bondi Junction on Thursday afternoon.

Two of them fled when approached by police, who then gave chase.

It's alleged the man stepped in front of one of the officers and punched him in the side of the head before fleeing.

"The constable attempted to block the hit with his left hand, injuring his thumb," NSW Police said in a statement.

The man - whom police later learned was subject to a freshly-issued revocation of parole warrant - was later arrested and charged with multiple offences, including assaulting a police officer causing actual bodily harm.

He was refused bail and is due to front Waverley Local Court on Friday.

It comes as the police union reissued calls for changes to infectious disease testing for officers injured on the job following an incident at Casino, in northern NSW.

It's alleged a senior constable was bitten on the upper thigh and a second officer punched and kicked by a man claiming to have AIDS.

The officers were trying to stop the man - whom they'd pulled over late on Saturday - from swallowing a plastic balloon.

He was wearing women's lingerie with his penis exposed and allegedly had a knife and syringes in his car.

"These two officers and their families now face an incredibly anxious wait have to find out whether they've been infected with anything," Police Association of NSW president Tony King said in a statement on Friday.

"What we need is the power to test the offender in order to provide some reassurance to the police and families involved."