Federal Opposition Leader Kevin Rudd has branded the Exclusive Brethren Christian sect a cult and criticised Prime Minister John Howard for meeting with the group's world leader.
Earlier this month, Mr Howard met with Bruce Hales, the "Elect Vessel" of the Exclusive Brethren, and with other leading members of the reclusive sect.
Australian Federal Police (AFP) are investigating the expenditure before the 2004 election of $370,000 on pro-Liberal and anti-Greens advertising by Willmac Enterprises, a company with links to the Exclusive Brethren.
The Brethren has been accused of running a smear campaign against New Zealand Prime Minister Helen Clark and hiring a private detective to investigate leading members of the New Zealand Labour Party.
Sect members are prohibited from voting, attending university, having TVs, radios, personal computers or mobile phones or contact with family members who leave the church.
Mr Rudd said he had real concerns about the impact of the Exclusive Brethren on Australian communities and, unlike Mr Howard, he refused to meet with its members.
"I believe this is an extremist cult and sect," he told reporters.
"I also believe that it breaks up families, I also believe that there are real problems with the provision of modern education to kids under their system where they, for example, are not given full range of access to information technology."
Mr Howard said he had done nothing wrong by meeting with representatives of the Exclusive Brethren.
"They're Australian citizens, its a lawful organisation and as prime minister I have met an enormous number of organisations," he told reporters.
"It's my job and I find it quite astonishing that people think its odd I have met representatives of a lawful organisation."
Mr Rudd said Mr Howard should reveal how much money the Brethren had donated to the Liberal Party and what undertakings had been given at the meeting with Mr Howard.
Exclusive Brethren spokesman Tony McCorkell said the delegation had not discussed anything political with Mr Howard at the meeting.
He said they had told Mr Howard they would pray for him and discussed the economy.
Mr McCorkell rejected Mr Rudd's claim the group was a cult.
"They are a Christian denomination which believes broadly the same as most other Christian denominations," he said.
Mr McCorkell said some Exclusive Brethren members had become politically active during the last election campaign because they had been concerned about then Labor leader Mark Latham's policies on private school funding.
He said he did not think members would be as involved in political campaigns at the upcoming election.
"Obviously, I don't speak on behalf of every member of the Brethren because they're free to do what they wish, but as a general rule I don't think you'd see what you saw last time," Mr McCorkell said.
Health Minister Tony Abbott said Mr Rudd was playing political games by refusing to meet with the Brethren.
"I don't see why he should ostracise them," Mr Abbott told AAP.
"They're perfectly good citizens.
"He's playing favourites among religious groups. Their theology is not my theology but they live perfectly respectable lives, they pay their taxes, they obey the law of the land.
"I don't know why Kevin Rudd has allowed himself to be spooked by them."