Police personnel at Sydney City Local Area Command, Kings Cross, Bankstown, Cabramatta – and even within senior management – have been implicated in an extraordinary attack on the Greens member for Newtown, Jenny Leong. The MP has been devastated by a string of Facebook posts that mocked her ethnic background and referred to her father as a "swamp monkey".

The cyber-bullying follows the Greens' latest bid, in the NSW Parliament, to repeal the state's controversial sniffer dog drug detection program. A Fairfax Media investigation has found that in one online attack, a city-based detective posted a modified image of Ms Leong's own Facebook profile picture, adding the words: "One condom could have prevented this from happening". The post was 'liked' by four other police employees including Detective Inspector Denby-Lea Eardley – a senior manager in Human Resources.

On Saturday, Ms Leong announced she had referred the matter to the Police Integrity Commission. In doing so, she called on NSW Police Commissioner Andrew Scipione to take immediate disciplinary action against those involved. "The role of the police is to protect the community from harmful and aggressive behaviour ... it is completely unacceptable they would be actively contributing to sexist and racist attacks," she said.

A NSW Police Force spokesman said that while the force is only in the early stages of investigating the posts, "it is clear they could contravene strict social media use policy".

He added: "Police officers are expected to behave at all times in a manner which upholds the integrity of their office and appropriate action will be taken against any found acting to the contrary."

On March 17, Ms Leong introduced a bill to the NSW lower house aimed at ending the use of drug detection dogs in public spaces without a warrant.

A day later, her Newtown office published a photo on her official Facebook page condemning the actions of two police officers seen patrolling a Sydney train with Tasers and sniffer dogs. The post said: "This kind of harassment and intimidation is exactly what the Greens' bill is aiming to stop."

Ms Leong said she had always anticipated a "lively" and "robust" political debate about the policy and bill. But what followed was an avalanche of criticism about the train post, swelled by a wave of unrelated, sexist and racially driven abuse, some of which was posted, shared, liked and applauded by police officers via their private Facebook pages. As Ms Leong's shocked staff worked to have the lewd posts taken down, they continued to be fanned across Facebook – with the aid of police involvement.

In her complaint to the PIC, she describes how one officer, allegedly based at Bankstown, changed his profile picture to an image of her, triggering a series of shocking comments. "The offensiveness of these comments is manifest," said Ms Leong.

As the MP's own Facebook page continued to be deluged by offensive material, police employees publicly celebrated the abuse – and contributed to it with other derogatory memes carrying her image. "Ha! Top Shelf!" said one officer based at Cabramatta who added: "Now people are posting screen shots of it back on her page!"

Another, at Sydney LAC, wrote: "She is still copping a smashing – love it!" He later added: "I haven't been banned yet and she is still getting it both barrels."

Under the Police Code of Conduct and Ethics, an employee must "behave honestly and in a way that upholds the values and the good reputation of NSW Police whether on or off duty."

In its Personal Use of Social Media Policy and Guidelines, staff are told: "Do not post any material that may bring the NSW Police Force into disrepute, or otherwise embarrass the agency."

More specifically, it states: "In posting to social media sites in a private capacity, do not make comments so harsh or extreme in its criticism of the government, a member of parliament, a political party, or their policies, that it raises questions about the employee's capacity to work professionally, efficiently or impartially."

Deputy Premier and Minister for Police Troy Grant said that while he "strongly disagreed" with the original post on Ms Leong's Facebook page, there is "no justification" for the "completely unacceptable." material that followed. "If these allegations are proven true against any police employee, sworn or unsworn, they will and should be held to full account," he said.

NSW Greens Police Spokesperson David Shoebridge likened the conduct to "hunting in a pack".

He said that whereas police had every right to hold political opinions and express them openly while off duty, evidence of "overt and aggressive attacks" on parliamentarians – and private citizens – was "disturbing."

"Our very understanding of a liberal democracy – where the police are non-political servants of the law – is at risk unless this conduct is censured and the culture that allowed it to happen addressed," said Mr Shoebridge.

Do you know more? eduff@fairfaxmedia.com.au