If a 60p top rate of tax raises no extra revenue the Scottish Greens would still back it, Patrick Harvie has said.

In an interview with STV's Bernard Ponsonby the Scottish Green co-convener admitted that he did not know how much extra revenue his party's preferred top rate of income tax would raise. Harvie said that he would continue backing the policy even if it did not generate more revenue.

Harvie said: "No, because I think it is an important point of principle that those who are extremely highly paid - their wealth is being generated by everyone in society.

"There has to be a tax band for these people on extreme high incomes. I don't think we should obsess about it we are only talking about 15,000 people out of the whole of the Scottish population."

The Scottish Green co-convener defended his stance saying that it "was about the principle that our society ought to care for everybody".

He said: "The principle that our economy belongs to all of us and the wealth that our economy is generated by all of us is not spite, it is about compassion.

"It is about the principle that our society ought to care for everybody and I would put to anybody in that situation who is contemplating either moving or employing a dodgy accountant to hide their income from the taxman, I would put to them that their well-being and their wealth depend on all of us as a society."

Harvie said that it was neither "sensible or rational" to give an exact date to when the North Sea oil and gas industry would close but "20 years" is a "realistic" time frame.

He said: "I think it is about looking at the long-term direction and recognising that perhaps over ten or 20 years we would be transitioning away from a reliance on fossil fuels. I think that is far more realistic than what the Scottish Government come out with saying there is another 40 or 50 years of oil and gas extraction."

Bernard Ponsonby then put it to Patrick Harvie that he was the equivalent of Margaret Thatcher to oil and gas communities:

At the recent Scottish Green manifesto launch Harvie's fellow co-convener Maggie Chapman stated that if 100,000 people signed a petition for second referendum then it would start the process. Chapman's comments were later clarified that instead the party favours 1m signatures.

Harvie said that if more people signed a petition against a referendum he "would respect their opinion" but no one has the right to say Scotland "doesn't have the right to ask this question again".

Election Face to Face features party leaders in the Holyrood elections being interviewed by STV News Political Editor Bernard Ponsonby:

It is screened on STV Glasgow and STV Edinburgh at 8.30pm and then on Scotland Tonight on STV at 10.30pm.