A pro-free-speech group has filed court papers suing Auckland Council and Mayor Phil Goff over the ban of two controversial "alt media" speakers from using city-owned venues.

In a statement today, the Free Speech Coalition said it had filed papers in the High Court at Auckland against Goff, the council and Regional Facilities Auckland (Auckland Live) under the New Zealand Bill of Rights Act.

Before filing proceedings, the group also wrote an open letter to the mayor suggesting he avoid the costs of litigation by entering into discussions with the promoters of Lauren Southern and Stefan Molyneux's speaking event, Axiomatic Media.

The Canadian pair, who were due talk at the Bruce Mason Centre on Auckland's North Shore next month, are known for holding far-right views on immigration, feminism and Islam.

In the coalition's statement of claim, Southern and Molyneux are said to promote themselves as "alt media".

The group's open letter to Goff describes what it claims were the council's lack of discussions over security concerns with the organisers or police, prior to Goff's tweet announcing the ban.

Let me be very clear, the right to free speech does not mean the right to be provided with an @AklCouncil platform for that speech.

— Phil Goff (@phil_goff) July 6, 2018

The letter also noted that the Canadian speakers' Australian tour was being hosted in local council or state government-owned venues.

"The coalition gets the impression the mayor is eager for the police to say they can't uphold their duty to keep the peace and protect free speech – a sad contrast with Australia that we never expected," the group's statement read.

Southern, who arrived in Australia last weekend, was banned from entering Britain this year for her part "in the distribution of racist material in Luton", according to the BBC.

The coalition also includes former Labour Party Minister Dr Michael Bassett, former leader of the National and Act Parties Dr Don Brash, business leader Ashley Church, and university lecturers.

Coalition member Melissa Derby, a University of Canterbury academic, said the council had made an "arbitrary and uninformed decision" which suggests "bias, prejudgment, and indifference" to the fundamental freedoms outlined in the Bill of Rights.

"It's regrettable to see the mayor digging his heels in when we have given him every opportunity to reconsider and avoid litigation costs," she said.

Coalition member Dr David Cumin, a University of Auckland lecturer and plaintiff in the proceedings, said Goff was now suggesting the ban wasn't about the speakers' political views, but about safety.

"What he risks is delivering a 'heckler's veto', where potential protesters get to decide who Aucklanders can hear from or associate with," he said.

"This action is to ensure that politicians and officials aren't allowed to discriminate against views they dislike when it comes to ratepayer-funded venues, regardless of how broadly 'unacceptable' the views might be."

The other plaintiffs in the proceedings are Axiomatic Media and Malcolm Moncrief-Spittle, a Dunedin bookseller.

A notice for an application for urgent and interim orders was also filed with the High Court, and asks for the event licence originally granted to Southern and Molyneux to remain in force until it can be reviewed by a judge.

Earlier this week, the coalition said it had exceeded its crowdfunding target of $50,000 to help pay for legal fees by more than 50 per cent.

With the additional funds, Jack Hodder, QC, was hired to act as lead counsel.