There will be a security review at Victoria's Parliament House after an anti-logging protester scaled the roof and abseiled down the front of the building.
The man spent hours hanging from the building on Wednesday before a rescue crew lowered him using a cherry picker attached to a fire truck.
Fellow activists cheered as the man was led away by police, who arrested two other men and a woman.
All were released and were expected to be charged on summons, police said.
The parliament's presiding officers said they regarded trespass as a serious matter and had options to take action under the Parliamentary Precincts Act.
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"The presiding officers cannot accept any protest that places people at risk and could include damage to property and involves an act of trespass," they said in a statement.
"(We) will be requesting that the incident be assessed fully as security matters are a priority for the presiding officers to ensure that members of parliament, parliamentary staff and visitors can go about their business safely."
The abseiling protester was part of the Whistleblowers, Activists and Citizens Alliance group, which wants the government to introduce more parks and reserves to protect wildlife, and create jobs in the environment sector.
"Under the Andrews Labor government, they have been logging native forests unlawfully and they're pushing some of Victoria's iconic endangered species to extinction," group spokeswoman Zianna Fuad told AAP earlier in the day.
Premier Daniel Andrews labelled the abseiler's stunt a "significant security breach".
Alliance activists in 2016 glued their hands to the railings of Canberra's Parliament House before abseiling down the front steps to protest against Australia's asylum-seeker policy.
