Threatening, sexist messages scrawled on balloons left at MP's office

South Australian state MP Jayne Stinson says staff arriving at her office this morning noticed balloons outside the front and in the car park.

But she said the matter "turned dark pretty quickly" when it became obvious the messages included "threats on my safety" as well as sexist names and other abuse.

SA Police is investigating and notes the incident has occurred amid an "increase in threats directed towards elected representatives".

A South Australian government MP says threatening, sexist and abusive messages scrawled on balloons — at least one of which contained powder — were left outside her office, in an incident that is being investigated by police.

Labor MP Jayne Stinson said staff arriving at her electorate office on Marion Road at Plympton this morning initially thought someone must have sent her balloons for her birthday.

But she said that upon closer inspection the matter "turned dark pretty quickly", when it became obvious the messages included "threats on my safety and my life".

She said the balloons had been left at the front of her office and in the car park.

SA Police has confirmed it is investigating the matter, noting it had come amid "an increase in threats directed towards elected representatives, candidates and others involved in public life".

Ms Stinson, who is the member for Badcoe in Adelaide's inner south-west, said several of the balloons had the words "stop the chop" scrawled upon them — a slogan associated with a public campaign opposed to government projects in the state's parklands.

"My staffer thought he was cleaning up and popped one of the balloons and got covered in powder, which of course is very frightening for someone," Ms Stinson said.

"Obviously at that point I told him to call the police, and the police arrived."

SA Police said while there were no injuries reported and no damage to property, "there was a threatening message left on one of the balloons, which police are investigating".

"Officers remind the community that threatening, intimidating or menacing behaviour is not acceptable and may constitute a criminal offence," police said in a statement.

"The current political and social environment has seen an increase in threats directed towards elected representatives.

"Everyone has the right to express their views peacefully and respectfully, however any conduct intended to cause fear, alarm or intimidation will be taken seriously and investigated by police."

The Plympton incident comes at a time of considerable public discussion about the safety of elected officials, prompted by alleged Wangaratta attack on federal MP Helen Haines.

Ms Stinson said she understood police were searching for two people believed to have left the balloons at her office.

"I don't know who has done this … [but] my message to those people is front up and let [police] know what you've done," she said.

"Protesting is fine, voicing your concerns to your MP is not just fine but encouraged — I welcome that — but when it steps over the line … that's just not on, that's not part of democratic exchange and it absolutely does not help people get what they want."

Ms Stinson said she had previously faced threats and attempted physical assaults during her two terms in office, and said she felt "really upset for my staff".

"They shouldn't have to come to work and deal with that," she said.

"They should feel safe in the workplace."