The Scottish Government is considering a "modest" rise in income tax for the country's highest earners, the First Minister has said.

Nicola Sturgeon sent her strongest signal yet that she is willing to put forward an income tax rise in her government's forthcoming budget.

The First Minister, alongside finance secretary Derek Mackay, spoke at a press conference on Thursday at the publication of a paper outlining different approaches the devolved administration could take.

The SNP has been seeking to build a consensus within Holyrood on the issue.

The minority government must rely on opposition support for it to pass the budget.

The First Minister admitted "nobody wants to pay more tax" but it may be only way to protect the country's public services.

Sturgeon warned income tax makes up only 30% of her government's budget, however, so it cannot solve all the administration's financial headaches.

"None of us want to see our cherished public services increasingly constrained in what they can deliver," said Sturgeon.

"So with all the pressures we now face, we must consider if the time has come for those who earn the most to pay a modest amount more to enable us to do so."

However, the Scottish Conservatives, who are the second largest party in the chamber poured scorn on the proposals during First Minister's Questions later on Thursday.

Conservative leader Ruth Davidson pressed the First Minister to commit to a "full, independent and thorough economic assessment of any tax changes before they are undertaken."

She added: "She all need to know if a tax rise will slow down growth in Scotland, compared to the rest of the UK."

The Tories want income tax rates and bands to remain the same.

On forthcoming budget negotiations, Mackay said: "We will engage in the discussions in an open-minded and constructive manner and, as the paper makes clear, the Chancellor's decisions on overall spending and tax policy for the rest of the UK are still critically important in determining Scottish Government funding, final decisions on tax and spend will be made in the proposed Scottish budget."