Paul Bunney, 63, has been charged and bailed to appear in Mount Barker Magistrates Court in May.

Ms Sharkie said the allegations were extremely serious and Mr Bunney has been told he cannot be part of her campaign.

"I have zero tolerance for the sort of behaviour alleged, no matter how passionate a supporter may be," she said in a statement.

"Every candidate has the right to feel safe in this campaign."

She said volunteers formed a major part of her push for re-election.

"More than 850 people have approached my office to volunteer their support in some capacity, big or small, for this campaign," she said.

Mr Bunney told online news outlet InDaily he never followed Ms Downer and the allegations stemmed from various interactions including an accusation he posted her address on Facebook.

Ms Sharkie is fighting to keep her seat at the May 18 election, while Ms Downer, the daughter of long-serving foreign minister Alexander Downer, is bidding to win back his former electorate for the Liberals.

Ms Downer also ran in last year's by-election in Mayo, called when Ms Sharkie fell foul of citizenship laws.

In that poll, Ms Sharkie increased her majority and now holds the seat with a margin of about five per cent.

Australian Associated Press