THE SNP must choose between aligning with “progressive” parties at Holyrood to advance equality or siding with “right-wing Tories” to keep down taxes, Patrick Harvie will say today.

The co-convener of the Scottish Greens will open his party’s annual conference in Perth with a warning to the Scottish Government designed to influence its budget in the New Year.

He will tell delegates at the city’s Concert Hall that pressure from the Greens has already pushed the minority SNP government into changes on carers, coal technology, and ending benefit sanctions under devolved employment schemes.

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However more needs to be done on the SNP’s “flawed” council tax reforms and fracking.

Mr Harvie told the Herald yesterday: “When it comes to budgets, it’s very clear the Scottish Government are going to have to work for support, and they have a simple choice.

“They can either work with the Conservatives, which would mean an inability to raise additional revenue from those who can afford to pay it and passing on austerity.

“Or they can look to the other side of the chamber where there are three parties who put forward different proposals to raise revenue from the wealthy and to protect public services.

“If the new powers coming to Scotland are for anything, they’re for giving Scotland the opportunity to go in a different economic direction.”

The SNP manifesto plan is to increase the threshold for 40p income tax payers in line with inflation when new tax powers kick in next year and leave the 45p additional rate untouched.

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Labour, the LibDems and Greens want income tax rises, while the Tories wanted lower tax.

But two votes short of a majority, the SNP needs one party’s help to pass its 2017-18 budget.

In his speech today, Mr Harvie is also expected to say: "To the SNP we will offer our support if they commit to meaningful, progressive change in Scotland.

“If they don't take that opportunity, they risk being remembered as a timid Government that caved-in to pressure from big business and sided with the Tories."

The Greens meet after their best Holyrood election since 2003, winning six MSPs in May, and its membership up five-fold to more than 8000 since the 2014 referendum.

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Mr Harvie said he believed the party would also have its best council result next year.

The Greens won 14 of Scotland’s 1222 councillors in 2012, most in Glasgow and Edinburgh.

Mr Harvie said they could double their numbers in both cities next May.

He declined put a target on councillor numbers, but said much of this weekend would focus on campaign training.

"Green councillors make a huge difference to their communities and it is vital we increase our influence to protect our public services.”