Multiple candidates during the 2025 election reported unusually large numbers of Liberal volunteers manning pre-poll booths, particularly in marginal seats.
Many were believed to be Plymouth Brethren Christian Church members mobilised by the church.
While individual members of the 16,000-strong movement could have decided to campaign, they were not backed by church funding, Brethren director Lloyd Grimshaw told a federal inquiry on Friday.
Earlier in the day, Nine newspapers reported members of the wealthy group engaged far-right public figures to lobby for the Liberals.
Mr Grimshaw said the allegations were a "complete lie" and denied the church's administrative board made donations to political parties.
He said the behaviour of members was distinct from that.
But the interference was "really disappointing" even if it was not coordinated by the church itself, inquiry chair and Labor MP Jerome Laxale said.
"To have that type of behaviour happening here, no matter who is behind it, is incredibly disturbing," he told News24.
"We've received reams of evidence, particularly about the Plymouth Brethren Christian Church."
Brethren members have been involved in conservative campaigning for many years.
In 2004, Brethren member Mark Mackenzie reportedly mounted a $370,000 campaign for the return of the Howard government.
Mr Mackenzie was still a director within the church, Mr Grimshaw confirmed, but did not know if he was involved in 2025 campaigns.
Central to the inquiry was a question of how much autonomy individual church members were given.
Mr Grimshaw denied claims made by Prime Minister Anthony Albanese shortly after the election that the Brethren church was a "cult".
"Not only is it offensive, but it's completely untrue, and it's hurtful," Mr Grimshaw said of the claims.
"We live in the normal suburbs with normal Christian families doing normal Christian things."
Greens senator Steph Hodgins-May called for other members of the church to be brought before the commission, as Mr Grimshaw was unable to answer many specific questions about Brethren structure.
The church's website confirms members are only permitted to eat and drink with those with whom they take Holy Communion, which is stated as the main difference from other Christian denominations.
Most members are born into the church, the website reads, but there are exceptions made for outsiders willing to commit to the church's "way of life".
Children attend an all-Brethren school which operates globally.
Most members of the sect do not vote.
Australian Federal Police commissioner Krissy Barrett would not be drawn on whether an investigation was needed, for the sake of national cohesion.
Home Affairs Minister Tony Burke said the allegations of political interference were chilling.
"No one should underestimate the significance of a democracy as cherished as ours, shifting to a pathway where physical intimidation gets paid for because of your political views," he told reporters in Canberra.
"We need to draw a line under this, we need to make sure that if this is what has happened in the 2025 election, that it is an aberration that is rejected by everybody today."
Mr Burke said the allegations were more alarming in the context of rising security threats levelled at federal politicians.
"The sharpest escalation I've seen in terms of the risk is where that physical intimidation might become something that is a fee for service," he said.
Coalition frontbencher Michael McCormack also called for an investigation into the claims.
"Whether it's the Plymouth Brethren or unions or whoever, they have a duty of care and a level of respect that they should bring to that parliamentary procedure and democratic procedure. That is not happening at the moment," he told ABC Radio.
"It shouldn't happen (from) anybody. It shouldn't happen from any side of politics. It shouldn't happen full stop."
