Members of an extremist Christian sect which has covered up child sex abuse have given secret, coordinated donations to the Liberal Party.

Dozens of Exclusive Brethren members - who practice a radical doctrine of "separation" and are not permitted to vote - donated more than $67,000 to the Liberal Party on the same day in December 2010.

The donations were revealed in documents tabled at the NSW Independent Commission Against Corruption during its inquiry into the source of funds flowing into Liberal Party coffers.

The Exclusive Brethren, recently rebranded the "Plymouth Brethren Christian Church", was described by former Prime Minister Kevin Rudd as "an extremist cult" which breaks up families. But the Liberal party operatives who accepted the en masse donations described them as "friends".

The church first came to public attention in 2006 when it was revealed the group had raised and spent $370,461 to influence the 2004 election on behalf of John Howard, with whom they were close.

Brethren members cannot eat or socialise with "worldly" people, and members who are excommunicated are usually prevented from seeing their families, including their own children. Their wealthy leader, Sydney-based Bruce D. Hales, has told his members to maintain an "utter hatred" of the rest of the world. He recently addressed a sermon to a mentally tormented young member of his flock saying it would be better to "finish yourself off" with poison than communicate with members of his own family.

Good Weekend today reveals that Mr Hales ordered that some victims of child sexual abuse be paid off to keep quiet. One victim was told his abuse was a "family matter," and nothing to do with the church, even though the church had placed the child with his abuser.

In 2003, the Brethren first excommunicated and then reinstated a man to the church despite overwhelming evidence that he had sexually abused two young girls who were living with him and attending the school where he was a trustee. The Brethren ignored the girls' letters, direct to Mr Hales, in which they begged him not to bring their abuser back.

The man was later convicted and jailed for offences including sexual intercourse with a child under 10.

The Brethren have issued a number of legal threats in recent weeks to try to stop the Good Weekend story being published. In a statement it said it was "misinformed and plainly wrong" to suggest the church had a problem with sex abuse. The Church "considers any abuse of any member of society abhorrent," the statement said.

Documents tabled at the NSW Independent Commission Against Corruption's Operation Spicer show 62 separate donors, all known members of the Brethren church, sent donations to the Liberal Party's alleged slush fund, the Free Enterprise Foundation.

Each donation was in individual amounts of $1500 or less, and appeared on a document labelled, "Friends".

According to the NSW Electoral Commission, the Free Enterprise Foundation was used to "channel and disguise" donations "by major political donors, some of whom were prohibited donors" to the Liberal Party. While individually the Brethren were not "major" donors, together their contribution was well above the legal disclosure threshold. It suggests they may have deliberately tried to avoid any need to disclose their collective contribution.

The donors are a who's who of senior Exclusive Brethren members in NSW, including relatives of Mr Hales, who is known to his followers as "the Elect" and is seen as next to God. Mr Hales' brother Stephen and sister-in-law Estelle Hales, and cousin John Hales donated $1490 each. Other families donated multiple times from different members. Five donations came from the Pridham family, who are relatives of Mr Hales.

Pump salesman Mark Mackenzie donated $1490 through his family partnership, Aline Pumps Sales and Service. Mr Mackenzie was the front man for the massive advertising spend by the Brethren on behalf of John Howard in 2004.

Brethren members run highly successful businesses, a network of charities, and received $26.6 million in government funding for their private school system.

Though they do not vote, the Exclusive Brethren have in the past been vigorous lobbyists of conservative Federal and state governments. They supported Mr Howard in 2004 to defend his school funding policy against then Labor leader Mark Latham. The Australian Tax Office has never scrutinised their habit of paying the vast bulk of their schools fees in tax-free donations and distributions from family trusts.

They are also virulently anti-gay. Their election funding in 2004 was directed to anti-gay, anti-Green and pro-Howard advertising. Similar campaigns took place the same year in New Zealand, Canada and the United States, in support of then president George W. Bush. The Brethren man coordinating the United States campaign said the group "like to fly beneath the radar".