The South Australian opposition wants disruptive protesters who potentially risk public safety hit with bigger fines and possible jail time.
Responding to a climate change protest in Adelaide, the Liberals have rushed to draft legislation increasing the maximum fines for public obstruction from $750 to $50,000 or a three-month jail sentence.
The legislation will be introduced into state parliament on Thursday with Opposition Leader David Speirs hoping it will be passed quickly.
It follows the action of a woman who abseiled over a city bridge and disrupted peak-hour traffic for about 90 minutes on Wednesday.
Extinction Rebellion South Australia said her action was to give a "life or death message" to delegates attending the nearby Australian Petroleum Production and Exploration Association conference at the Adelaide Convention Centre.
Mr Speirs said it proved costly for businesses and there were reports people had been delayed attending appointments at the nearby Royal Adelaide Hospital.
"These types of protests are getting out of control and we are sick and tired of seeing groups and individuals receive nothing more than a slap on the wrist," he said.
"We believe in every South Australian's right to protest, but in a peaceful way that is respectful of those who chose to go about their daily lives.
"What we saw yesterday from Extinction Rebellion was outrageous and unacceptable."
Greens MP Robert Simms said such legislation to curtail the right to protest was "chilling".
"Draconian anti-protest laws were rushed through state parliament in NSW. It's very alarming to hear that South Australia may be next," he said.
"The right to peaceful protest and civil disobedience are fundamental to our democracy."
In a third day of action, Extinction Rebellion activists targeted the Santos headquarters in Adelaide on Thursday, again disrupting traffic.