Representatives of the Aboriginal Tent Embassy have identified unionist Kim Sattler as the person who told indigenous people on Thursday that Opposition Leader Tony Abbott was in a Canberra restaurant.
About 200 people surrounded the restaurant after they had incorrectly heard that Mr Abbott had called for the destruction of the Tent Embassy which is situated opposite Old Parliament House.
Tony Hodges, a media adviser to Prime Minister Julia Gillard, resigned on Friday after revealing that Mr Abbott was inside the restaurant.
The person believed to be Kim Sattler passed the information on to Tent Embassy representatives.
Ms Sattler is the secretary of Unions ACT.
"This person said Tony Abbott is in the coffee shop talking to the press about closing down the Aboriginal Tent Embassy," Tent Embassy representative Barbara Shaw told reporters on Saturday.
"She clearly stated 'tell people'. So that's what I did."
"They (media representatives) clearly stated that it was Kim Sattler speaking to me. It's recorded on a number of videos.
"I know who she is now. Thursday afternoon I didn't know who she was."
Ms Shaw identified a photograph of Ms Sattler which was handed to her.
One of the founders of the Aboriginal Tent Embassy, Michael Anderson, said Ms Sattler had spoken to him as well.
"There was a lady running around here when I was doing a radio interview and she said the prime minister's office wants to talk to you and I thought she was joking and said I'll talk later," he told reporters.
"I know that woman to be Kim Sattler."
Mr Anderson said Ms Sattler recognised who he was.
"She came and then she went away and, because I didn't respond, she went to other people," he said.
"All she said was 'Michael, the prime minister's office would like to talk to you."'
Gillard's office said that although the Hodges had not suggested or encouraged violence or demonstration, the release of the information was "an error of judgment."
Michael Outram, national manager of protection for the Australian Federal Police, said police may file charges against some of the protesters. Protest leaders denied doing anything wrong, accused the police of manhandling protesters and said they planned to lodge a complaint against the officers involved.
About 200 indigenous-rights supporters marched on the nation's Parliament House on Friday, burning an Australian flag in front of a wall of police and carrying signs with messages such as "All cops are bastards." No one was hurt and the protesters left minutes later.
The restaurant where Thursday's clash occurred is close to the so-called Aboriginal Tent Embassy, where the protesters had demonstrated peacefully earlier in the day. That long-standing, ramshackle collection of tents and temporary shelters is a center point of protests against Australia Day, which marks the arrival of the first fleet of British colonists in Sydney on Jan. 26, 1788. Many Aborigines call it Invasion Day because the land was settled without a treaty with traditional owners.
The Tent Embassy celebrated its 40th anniversary on Thursday, and Abbott had earlier angered activists by saying it was time the embassy "moved on." Abbott said Friday that his comment had been misinterpreted, and that he never meant to imply the embassy should be torn down.
Despite acceptance by other indigenous leaders that the comments had been misinterpreted by protesters, and reports that elders were considering expelling some activists responsible for the violence, protesters were furious at Abbott.
"He made the comments in an inciteful and smug manner in Sydney and then flies several hundred kilometres to come down and sit 100m from us," Tent Embassy spokesman Mark McMurtrie told ABC radio.
They blocked Commonwealth Ave, a major thoroughfare leading from Parliament House to the city and pushed back police with dogs guarding the forecourt of Parliament House, which is laid out with indigenous designs.
After chanting and burning a flag, they returned to the Tent Embassy.
Earlier, political and indigenous leaders had tried to cool passions.
The nation rarely sees trouble on its national day. Although many Aborigines call the celebration "invasion day" and bear strong grievances, nothing of this intensity or passion has scarred Australia Day for decades.
Protesters were furious at reports that Abbott had said it was time for the Tent Embassy to "move on".
Yesterday Abbott told ABC radio that his remarks had been misinterpreted and he was making the point that the neglect of indigenous issues that sparked the launch of the embassy in 1972 no longer existed.
"That might have been true 40 years ago. It certainly isn't true today.
"That's why I think the sense of grievance which motivated the establishment of the Tent Embassy all those years back ought not be as intense today. And that's why I said I thought it was time to move on.
"Now I certainly didn't say what was attributed to me and I think it was most unfortunate that some people in that crowd verballed me and as a result stirred people up."
One of the embassy's founders, activist Michael Anderson, said being told that Abbott had said it was time the protest centre moved on had been like a red flag to a bull.
But he told Melbourne radio 3AW after seeing a transcript of Abbott's remarks: "When I looked at the Tony Abbott thing, of course when he said 'It's time to move on', yeah, people misinterpreted that and unfortunately it provoked an incident."
He said Tent Embassy organisers had not provoked the violence.
"It's just the people who were here found out that [Abbott] was there and they ran," Anderson said.
"You can't blame the organisers for that because we didn't organise it. It was a spontaneous reaction [and] it got out of hand."
Anderson said some of the agitators could be asked to leave by elders, but said the only apology due to Gillard and Abbott should come from the police, who he claimed had over-reacted.
Gillard said she had been confident in the ability of the police to protect her and Abbott but was furious that the protest had disrupted a ceremony to award national emergency services medals.
"What I utterly condemn is when protests turn violent, the way we saw the violence yesterday, and particularly disrupting an event which was to honour some extraordinary Australians, did leave me very angry," she said.
Indigenous leader and former national Labor Party president Warren Mundine condemned the violence yesterday, telling ABC radio yesterday that Abbott's remarks had been "pretty timid" and echoed his own beliefs.
"Quite frankly [the Tent Embassy] is irrelevant to the mainstream of Aboriginal people today and it has been for the last 20 years," he said.
Aboriginal and Torres Strait Islander Social Justice Commissioner Mick Gooda said he had been appalled by an "aggressive, divisive and frightening protest".
"While we need to acknowledge that there's a real anger, frustration and hurt that exists in some Aboriginal and Torres Strait Islander communities around Australia, we must not give in to aggressive and disrespectful actions ourselves.
"Aggressive behaviour was not acceptable 40 years ago to the original early campaigners at the Tent Embassy and it is not acceptable today."