PATRICK Harvie has suggested that imposing increased taxes on higher earners will be the price of Scottish Green support if his party is to back SNP spending plans, as he warned Nicola Sturgeon against making deals with the Tories.

The party co-convenor, who was reelected in the Glasgow region as the Greens trebled their cohort of MSPs to six, said the SNP membership was at odds with its leadership's tax policy, as he looked ahead to negotiations over the Scottish Government budget.

The nationalists went into the election saying they would keep income tax the same as the rest of the UK, with the exception of increasing the higher rate threshold by inflation, rejecting calls from the Greens, Labour and the Liberal Democrats to raise tax rates to invest in public services.

With the SNP short of a majority, the party will have to seek a cross-party consensus to have its plans passed. It faces the prospect of making a deal with the Tories, who wanted an above-inflation rise in the middle rate threshold, or parties that had put forward more left wing proposals.

Mr Harvie, speaking to journalists in Edinburgh the day after the country went to the polls, said: "I would question the notion that the Tories are necessarily closer to the SNP’s position. It may be close to the position their manifesto set out, but I think a great many members of the SNP would like to see them go further.

"I think the SNP will find themselves quite uncomfortable if they choose to make alliances with the Conservatives only on the financial approach to the use of the new taxation powers.

"I would be surprised if the SNP decided that the best way of serving the interests of the voters and the members that have taken them to the position that they’re in at the moment is simply to align with the Conservatives.

"I will certainly make the effort, as the whole group will, to ensure they have progressive options rather than simply handing on Tory cuts to public services in Scotland. The case for progressive taxation is strong, and they (the SNP) are going to require support to get a budget through."

The Green tally of half a dozen MSPs is only one fewer than the record seven it achieved in 2003. While the party had targeted representation in each of Holyrood's eight regions, Green sources have declared themselves delighted with the result, which saw the party replace the Liberal Democrats as Holyrood's fourth largest party.

Mr Harvie has continually promised that he would seek to push the SNP into more radical positions, with the nationalists lack of a majority potentially handing the smaller party unprecedented influence.

The Green co-convenor said: "We've always - whether it's been facing a Labour-Lib Dem coalition, a minority government or a majority government - we've always been willing to be constructive where there is genuine common ground, we find this far more productive, and where necessary challenge where there are disagreements."