GREEN MSP Patrick Harvie challenged the SNP to commit to “meaningful progressive change” or lose the support of his party at the opening of the Scottish Greens’ autumn conference yesterday.

Speaking to delegates in Perth, party co-convenor Mr Harvie warned that the Scottish government had “missed a key opportunity to prove its progressive credentials by reforming the council tax and supporting Green proposals for a fairer alternative.”

He also warned that there were “many more tests to come” and said it was “unthinkable” that First Minister Nicola Sturgeon could set a credible green agenda “while backing Heathrow expansion and cutting air passenger duty.”

Mr Harvie argued that in the future Ms Sturgeon’s minority government will  have to choose between the “progressive” backing of his party or that of the “right-wing Tories.”

The Scottish Greens’ strength at Holyrood increased threefold after the May elections, with the party going from two MSPs to six.

An SNP spokesman said: “In government, the SNP is happy to work with other progressive parties and will always listen carefully to constructive suggestions.”

Meanwhile, transport union RMT announced that it would lobby the Scottish Green Party’s conference today on its two key campaigns — Safer Scottish Trains and Save our Seafarers.

General secretary Mick Cash said: “RMT recognises the importance of having direct contact with activists from political parties like the Scottish Greens as we work to persuade grassroots members of the importance of our fight for public ownership and safety on Scottish railways and the twin campaign to force the plight of our maritime industry up the agenda.”