SCOTTISH Greens last night warned the Government that they would vote against the SNP's budget unless three key tests were met over anti-austerity.

Finance secretary Derek Mackay needs the backing of the party to ensure his spending plans for 2018-19 are passed by MSPs on January 31.

Scottish Green co-convenor Patrick Harvie said Mackay had to be more generous on public sector wages than the Government's existing commitment to lift the one per cent pay cap.

He added that Mackay must also reverse £157 million of cuts to councils that the Greens claimed were part the draft budget published last month.

The Green MSP said additional funds for projects to tackle climate change were another condition for Green support. "The ball is in the Scottish Government's court," he said.

"If the Government come back before January 31 with a revised budget that does not meet these three tests, we will be unable to give our support."

A joint report by the Jimmy Reid Foundation and Unison also warned that cuts to the most basic services will see the poorest Scots “unable to cope”. It said that local councils had become the "poor relation of the public sector in Scotland”.

A substantial public sector pay increase, it added, would give workers greater spending power and grow the economy.

A spokesman for the finance secretary said: "The Greens have set out their proposals, and any other party interested in serious negotiations is welcome to do the same."