A booking at the Dunedin City Library for a group that opposes sex self-identification has been cancelled.

"We strive to ensure our libraries offer an environment where all members of our community can feel welcome and safe," a tweet from the Dunedin City Council said.

The June 17 booking was for Speak Up for Women New Zealand, which describes itself on its Facebook page as a non-partisan organisation that exists to protect and advance the rights and interests of women and girls.

However, the group has been branded anti-transgender by activists.

In its promotion of the meeting, Speak Up for Women New Zealand said the Government intended to push through a law change this year.

"This law is not only unpopular and unscrutinised, it also has wide-ranging implications for the rights of women and girls."

The Births, Deaths, Marriages, and Relationships Registration Bill would enable people to self-identify their sex on their birth certificate without going to the Family Court, Minister of Internal Affairs Jan Tinetti has said.

"This Government understands that self-identification is a significant issue for transgender, non-binary and intersex New Zealanders, and is committed to making it easier for people to formally acknowledge their identified gender.”

The Dunedin City Council’s cancellation of the booking followed a similar move by the Christchurch City Libraries.

The Free Speech Union has asked the Christchurch City Council to explain its decision.

"This decision totally ignores the Court of Appeal’s decision issued last month confirming that council-owned venues must uphold free speech," union spokesman Dr David Cumin said.

"De-platforming these debates undermines the very heart of democratic participation — precisely the events civil venues were built for."

National Party leader Judith Collins has called the Christchurch decision disappointing.

grant.miller@odt.co.nz