Increasing income tax to 50p for top earners in Scotland right now would be "daft" and "reckless", Nicola Sturgeon said, as she hinted a future SNP government could raise the rate in the future.

The First Minister said her party would not increase the highest rate "straight away" but said the matter could remain under consideration.

She made the comments the day after the SNP unveiled its plans for income tax in Scotland, an issue which will be key in May's Scottish Parliament election.

With Holyrood to have power over income tax rates and bands from April 2017 onwards, the political parties have been laying their proposals before the voters.

Ms Sturgeon was pressed on her party's proposals as the leaders clashed at First Minister's Questions at Holyrood for the last time this session.

She told MSPs that if Scotland was to restore 50p tax rate for those earning £150,000 without the rest of the UK following suit, the country risked losing millions of pounds in revenue as high earners could move south.

The First Minister said: "Raising the top rate of tax would be politically easy to do, there are only 17,000 people in our country that pay it.

"There's no political risk attached to doing that. But doing it in the face of analysis that says that right now it could actually reduce the amount of money we have to invest in our National Health Service and our public services would not be radical, it would be reckless, it would not be daring, it would be daft.

"So, we will not do it straight away. Instead, we will continue to consider it in light of our experience and analysis."

Under the SNP's income tax plans, the basic rate of 20p will be frozen for the five years of the next Scottish Parliament term, with no increases in the the 40p and 45p rates next year.

Ms Sturgeon's party will not raise the threshold for the 40p tax rate to £45,000 as the UK Government proposes in April 2017.

Scottish Labour leader Kezia Dugdale hit out at the SNP plans, saying: "A nationalist First Minister arguing that Scotland can't go it alone on tax really takes the biscuit."

Ms Dugdale stated: "The SNP will now go into this election with a commitment to keep George Osborne's tax cut for those earning more than £150,000, even though we now have the power to make different choices from the Tories."

The Scottish Labour leader continued her attack, saying while the First Minister "has power to reverse George Osborne's tax cut for the very richest and stop the cuts, she refuses to use it.".

Ms Dugdale said: "This is the First Minister who made her name as the anti-austerity champion, she went down to England and said she would stand up to George Osborne's tax cuts, and yet the minute she gets the powers back home the First Minister chooses not to act."

She went on: "This First Minister, who has campaigned for years on the mantra that more powers means fewer cuts, now refuses to use the powers to stop the cuts.

"The First Minister who says education is a priority won't ask the richest 1% to pay more to invest in our schools.

"The SNP say they are anti-austerity but they are content to use this parliament as a conveyor belt for Tory cuts."

The Labour leader said Scotland had lost 4,000 teachers and 152,000 college places since the SNP came to power, adding the "gap between the richest and the rest in our schools is as wide as ever".

She told MSPs the new tax powers coming to Holyrood "mean we can change that" as she said Labour could protect education spending over the next five years because of its plans to raise the basic rate of income tax in Scotland by 1p

"The SNP tax plans don't raise anywhere near enough to do the same," Ms Dugdale said.

Ms Sturgeon insisted her party's income tax plans, combined with higher council tax charges for those living in the most expensive homes, would raise £2 billion over the course of the next parliament.

She said: "We will ask the better-off in our society to shoulder a bit more of the burden and over the life of the next parliament our proposals local and national will raise an additional £2 billion of revenue, revenue we can invest in our National Health Service, in our public services and in mitigating the impact of Tory austerity."

The First Minister warned if Scotland alone increased the top tax rate to 50p and 7% of the highest earners left the country, the country could be £30 million a year worse off.

She told MSPs: "I'll get on with doing the right thing, that is why we are asking people in the top 10% of income earners in our country to forego the George Osborne tax cut, it is why we are asking those living in the biggest houses in our country to contribute a little bit more, so that over the next parliament we can generate an extra £2 billion to invest in our National Health Service, to invest in our education system, to mitigate against Tory austerity."

She told Ms Dugdale: "I'll leave Labour, given it remains in a battle for second place in this election, to indulge in political gestures.

"I will get on with putting forward the proposals that will see this country governed fairly and progressively."

The SNP leader continued: "The tax proposals we will be proud to put forward in this election will raise an additional £2 billion for our public services and to enable us to mitigate against Tory austerity.

"What we have in this chamber is Tories telling us we're taxing too much, Labour telling us we're not taxing ordinary working people enough.

"I suspect the people of Scotland will look at what we're offering and say it is right, proper and sensible and progressive, that is why they will choose us to continue to govern this country."