The Scottish Green Party’s co-leaders have warned that the coalition with the SNP will dissolve if the new leadership fails to back its key principles.

In what will be seen as a message aimed particularly at Kate Forbes, Patrick Harvie and Lorna Slater said that the gender issue is “non-negotiable”, alongside commitments on the environment.

Ms Forbes was on maternity leave at the time of the vote on the Gender Recognition Bill and has since said that she would not have supported it.

This prompted speculation that if she became First Minister she would not work with the Greens in government. On Friday she said she would “negotiate” with the Greens.

Addressing the Scottish Green Party conference in Clydebank today, Ms Slater, who is also one of two Green ministers in the government, said: “We have unfinished business. I want us to stay in Government and see through the change we have begun. But not at any cost. We will never be a party that is prepared to put our principles to one side.

“We will only vote for the SNP’s new Leader to become First Minister if they are committed to the politics of cooperation. 

“If they respect and share our values of equality and environmentalism. If they will prioritise climate justice. And if they agree that trans rights are human rights and that our trans siblings cannot be used as political fodder by Westminster.”

The Greens became part of the Scottish Government in 2021 in exchange for support for SNP policies. Mr Harvie also has a ministerial post.

In his speech to conference he said: “If Monday sees a First Minister we can work with, and we deliver on our promises, we can go into the next election for the first time with a track record as a party of government, showing the results you get when you vote Green.

“If we do that, we will give ourselves the chance to continue to shape the politics of this country in the critically important years ahead.”

During a visit to the Zakariyya Masjid mosque in Wishaw, North Lanarkshire, on Friday afternoon, Ms Forbes said: “I want to work with Patrick Harvie and the Green Party.

“I have negotiated probably more than any other Cabinet Secretary with the Greens in the past, and I want to work with other parties in Holyrood.

“I would certainly have a conversation with him very early doors.”

On whether compromise over the gender reforms is possible, she said: “I would hope that as a member of Government, we could both take an approach which is to consider the legal advice, and to make decisions off the back of the legal advice.”

The new leader of the SNP will be declared on Monday.