A fire at the doors of Old Parliament House in Canberra has caused extensive damage to the front of the building as protesters were dragged away by police.
ACT Emergency Services were called to the scene to find the front doors alight just before noon on Thursday.
The building was evacuated as a precaution and crews extinguished the blaze.
Social media footage shows police dragging protesters away from the front steps of the building. It also shows a large fire burning on the doors.
The building was set on fire by protesters on December 21 and there have been daily protests outside it since December 26.
Deputy Prime Minister Barnaby Joyce said it was "an absolute disgrace" if the fire was deliberately lit.
"This is the parliament that for so long underpinned the freedoms we have as a democracy and made the decisions that formed us as a nation, fighting for the increase of rights and corrections to our colonial past," he said.
"If someone is trying to make a statement then it is a very bad one that will be received with overwhelming disgust."
Former deputy prime minister Michael McCormack said repercussions should be "swift and severe" if it was arson.
"An outrageous attack on our democracy, our history and sovereignty," he said.
"This penchant for tearing down our past serves no purpose."
Opposition Leader Anthony Albanese said it was a "very historic building".
"I had the great honour of working for Tom Uren in that building. It's used by school groups, it's used for educational purposes as well as for functions," he said.
"It's an important building and I just hope that there is only minimal damage."
The building is now home to the Museum of Australian Democracy.
