Members of the Scottish Green Party have voted to suspend ties with their sister party south of the border, backing a motion which accused it of failing to tackle transphobia.

At their conference in Dundee, Scottish Greens chose to suspend formal ties with the Green Party of England and Wales (GPEW) until the latter addressed “both issues of transphobia and respect for the Scottish Green Party”.

While the two parties are separate organisations, the English and Welsh party has said that it values its links to Greens in Scotland.

The suspension of ties means GPEW members will not be able to automatically attend certain meetings of the Scottish Green Party but it will not stop informal cooperation.

Guy Ingerson’s motion said office-bearers in GPEW had recently “engaged in transphobic rhetoric and conduct”.

It also said office-bearers had “insulted” the Scottish Greens, claiming disciplinary action from GPEW had been “lethargic, ineffective and inconsistent”.

The text of the motion reads: “The suspension of this association will remain in effect until such time that action is taken that satisfies the membership of the Scottish Green Party, through conference or SGP Council, to address both issues of transphobia and respect for the Scottish Green Party, our independence as a party, and the devolution settlement.”

Scottish Green members overwhelmingly backed the motion when it came to a vote towards the end of the party’s conference on Sunday.

Following the vote, Green member of the London Assembly Sian Berry said she was saddened by the decision but added the party had “many problems left to solve”.

She tweeted: “For many E&W Greens, today’s @scottishgreens decision is a sad thing to hear, but it has a basis.

“Fine words are fine, but I said this when I stepped out of the leadership by-election last year, and we still have many of the same problems left to solve.”

A spokesman for GPEW said: “The Green Party of England and Wales values highly our relationship with our sister party, the Scottish Greens, and we are proud of the aims and values that we share in furthering Green policies across the UK.

“The Green Party of England and Wales is clear that trans rights are human rights and we are proud of our strong policies on trans inclusion.

“It is our priority to champion diversity and be a welcoming and inclusive party for all – that means campaigning for the rights of trans people, women and all oppressed groups, as the Green Party has always done.”

Zack Polanski, deputy leader of GPEW, addressed the Scottish Greens’ conference on Saturday ahead of the vote on Sunday.

He said: “We know as Greens we will stand with all marginalised communities, whether that be disabled people, refugees, and of course the trans community.

“I’ll say it once and I’ll say every time – there is no LGB without the T.”

The trans community has been at the “centre of a conservative culture war”, he said.

Patrick Harvie, co-leader of the Scottish Greens, earlier said the GPEW has an “internal fight” to hold on to its progressive values but he did not express a preference about the motion.

A spokesman for the Scottish Greens said: “Trans and non-binary rights are human rights, and the Scottish Greens will always stand with our trans siblings, even when it means telling difficult truths to our friends.

“We will continue to work with champions of LGBTQ+ rights in GPEW, such as deputy leader Zack Polanski who we were delighted to have join our conference this weekend.”