Nicola Sturgeon said the authorities cannot be sure there are no other Scots affected.
Sturgeon: Tax Decisions "Will Be Right For Scotland"
Nicola Sturgeon branded Conservative plans to increase the threshold for the top rate of income tax as the "wrong'' decision and told MSPs: "It is not a choice I am going to make myself.''
The First Minister was pressed on how she would use new powers over the charge, which are coming to Scotland from 2017.
MSPs will have control over income tax rates and bands from April next year, with the SNP yet to set out what its proposals for the levy are.
Ms Sturgeon said the party will outline its tax plans early next week, but Scottish Conservative leader Ruth Davidson raised fears that some people north of the border could pay more tax than those earning the same amount in England.
She warned of the impact a sign on the border saying "higher tax here'' could have for Scotland.
But Ms Sturgeon insisted she would "take decisions that are right for Scotland''.
Four times during First Minister's Questions at Holyrood, she condemned Chancellor George Osborne's decision to raise the threshold for the top rate to £45,000 as the "wrong choice''.
She told MSPs: "If I think it is the wrong choice it is not a choice I am going to make myself.''
She added: "I think George Osborne's decision to cut taxes for 10% of the population at the highest end of the income spectrum is the wrong choice and I will not take that same choice.''
She was repeatedly pressed on the issue by Scottish Labour leader Kezia Dugdale, with Ms Sturgeon insisted after she had replied four times "surely somebody on the Labour benches must have understood it''.
Ms Dugdale began the exchanges by asking Ms Sturgeon for her views on what she described as being a "typical Tory Budget''.
The Scottish Labour leader insisted: "When our schools are facing cuts and thousands of people are losing their jobs, tax cuts for high earners cannot be the priority.''
Her party would reverse this, Ms Dugdale said, as she demanded to know if the SNP would do the same.
The First Minister said detailed income tax plans "based on what is right for Scotland now and in the long term'' would be unveiled early next week.
But she added: "Let me be absolutely clear today, a large tax cut for 10% actually of the population, those on the highest incomes, at a time when support for the disabled is being cut and at a time when our public services are under pressure, is in my view the wrong choice.
"I think that money should be invested in our public services and in protecting the vulnerable.''
Ms Dugdale claimed that "was anything but a clear answer from the First Minister'', adding: "Nicola Sturgeon has said it is the wrong choice, but she hasn't said she would take a different one when she has the power to do so.''
The SNP leader hit back: "For any fair minded person who was actually willing to listen to my answer it was a very, very clear answer indeed.
"I said that the choice of giving a fairly hefty tax cut to 10% of the population, the highest income earners in our country, was the wrong choice. I think that is fairly clear.
"I then said we would set out our plans for income tax early next week, I've always said we would set them out prior to the dissolution of Parliament and that is what we will do.
"But finally I said we should and would choose to invest that money instead in our public services and protecting the vulnerable. For anybody who is fair minded, listening to what I said, I think they will find that a very clear answer indeed.''
Ms Dugdale continued to question her on the issue, with the First Minister telling her: "People watching this are starting to laugh not with but at her, as she pointedly refuses to hear what I am saying.''
The Scottish Labour leader responded: "I think people watching this at home are wondering why the First Minister can't answer a question with a simple yes or no answer.''
She highlighted the SNP's refusal to back Labour plans to up the basic rate of income tax in Scotland by 1p - a power Holyrood currently has which could raise almost £500 million.
Ms Dugdale said: "The First Minister tells us she is against the cuts and opposes Westminster's austerity agenda. But when faced with a choice between using the powers of this Parliament to invest or carrying on with the cuts, the First Minister chooses cuts and refuses to use the powers.
"She's just stripped £500 million out of school budgets and the services of vital public services.''
But Ms Sturgeon told MSPs: "This line of questioning from Kezia Dugdale reminds me a bit of the Labour Party in Scotland generally - going absolutely nowhere.''
She added: "When Kezia Dugdale was scripting her questions you would have thought she would have factored in the possibility I would have answered the question at the first time of asking, and then have the ability to amend the questions that come later.
"Let me say for the fourth time, I think George Osborne's decision to cut taxes for 10% of the population at the highest end of the income spectrum is the wrong choice and I will not take that same choice.''
Ms Davidson also pressed the First Minister on income tax.
She asked what "detailed analysis'' the Scottish Government has published, before going on to add that the issue of how to use the new powers has not been discussed by experts on the First Minister's Council of Economic Advisers.
The Scottish Conservative said: "There has been no analysis or evidence base put forward, and you can run through the minutes of the First Minister's Council of Economic Advisers at any point in the last year and incredibly the new tax powers don't even merit discussion amongst them.''
Ms Davidson added: "I am clear I don't want to see a sign at the border which says 'higher taxes here' because I think that is the wrong choice for Scotland.''
She told MSPs that former Scottish Enterprise chief executive Jack Perry supported that view, and had warned "A further tax grab will only weaken our tax base and depress the economy. That will do nothing to help support schools, hospitals and the ageing population.''
The First Minister again said the SNP would publish its income tax plans early next week, saying at the same time it would set out "the analysis that backs up the decision we have taken on income tax''.
She hit out at Ms Davidson, claiming the Tory would not use the new income tax powers at all and is "simply going to mimic George Osborne''.
Ms Sturgeon said: "I'll set out my proposals on income tax. But Ruth Davidson is not proposing to use the income tax powers.
"She is not proposing a single iota of difference from the tax proposals of George Osborne.
"She is going to mimic George Osborne. I'm going to take decisions that are right for Scotland.''
Family members say Laura Macintyre and Eilidh MacLeod haven't been heard from since the explosion.
The families of two girls from the Western Isles missing after attending the concert in Manchester targeted in a terror attack have issued appeals on social media.
Crews were called to the former Royal Victoria Hospital site this afternoon.
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