Controversial conservative politicians Cory Bernardi and George Christensen have agreed to help an anti-Islam organisation raise funds to defend a defamation case brought by a halal certifier.

The South Australian senator and Queensland MP, who are both outspoken critics of Islam and halal certification, are on the bill for a series of events by the Q Society, the Australian reported.

Last year Mohamed El-Mouelhy, the director of Halal Certification Australia, launched legal action against the organisation and three of its members over two videos posted on YouTube in 2013 and 2014.

The defendants include Kirralie Smith, a NSW Senate candidate for the Australian Liberty Alliance who narrated the videos, and Debbie Robinson, national president of the Q Society.

Christensen told Guardian Australia he had been asked to appear “to assist my good friend Kirralie”.

“I will be speaking in support of free speech and against political correctness.”

Bernardi, who has made accusations against El-Mouelhy under parliamentary privilege, told the Australian he was helping Smith as a “true friend”, and was “more than happy to ­assist in raising money to fund the legal defence of a friend against Mohamed El-Mouelhy”.

The Australian Liberty Alliance (ALA) launched in 2015 as a far-right political party campaigning on an anti-Islam and anti-immigration stance. Smith has previously joked that president-elect Donald Trump had “stolen” the ALA’s ideas.

Its rise reportedly drew members from disaffected Coalition supporters, Christensen telling Fairfax in April the ALA was “definitely taking rank and file LNP supporters”. He didn’t fear the ALA would become a threat to the party.

George Christensen attended a previous Q Society event when the Dutch far-right anti-immigration campaigner Geert Wilder visited Australia. Photograph: Mike Bowers/The Guardian

Robinson told Guardian Australia the guests would be addressing the crowd at the events. Bernardi had been invited by Smith, who knew the senator from his inquiry into halal certification, she said.

Christensen had attended a previous Q Society event when the Dutch far-right anti-immigration campaigner Geert Wilder visited Australia.

Q Society describes itself as Australia’s “leading Islam-critical movement”, and has called for a 10-year moratorium on immigration from Organisation of Islamic Cooperation countries, and for Australia to withdraw from the “hijacked” UN refugee convention.

It has also heavily campaigned against halal certification and section 18C of the Racial Discrimination Act.

Next year’s events seek to raise funds for the group’s legal defence against El-Mouehly’s suit. In a letter appealing for donations, Robinson said: “It is vital that those who speak the truth about Islamic halal certification and other Islamic impositions are not silenced by time-consuming and expensive court action.”

According to a statement of claim filed in the action, the videos posted by the defendants made several defamatory imputations about El-Mouelhy, including that he sought to mislead and deceive the general public, was pushing for sharia law in Australia, and was promoting “a global push for Islamisation calculated to destroy Australia values of freedom and tolerance”.

It also allegedly suggested he was “un-Australian” and “reasonably suspected” of financially supporting terrorism, and the second video contained imputations including that El-Mouelhy was part of a conspiracy to destroy western civilisation from within.

El-Mouelhy was seeking damages, aggravated damages, interest and injunctions against further publication of the imputations.

A trial has been set down for four to five weeks in the NSW supreme court next year.

Angry Anderson, cartoonist Larry Pickering and Sky News presenter Ross Cameron are also on the bill.

In a video spruiking the events, Smith described the lineup as “a dream come true”, and praised Christensen and Bernardi for their outspoken brand of conservatism.

She suggested people buy themselves a ticket “for Christmas or Hanukah”.

Bernardi’s office has been contacted for comment.