Nicola Sturgeon's Valentine's Day date for a deal to be agreed over Scotland's future funding arrangements is an "artificial deadline", Downing Street has insisted.

Protracted negotiations are taking place between the Scottish Government and Westminster over how the block grant will be affected when Holyrood gets new tax-raising powers.

Deputy First Minister John Swinney, who has already held a series of meetings with the Treasury, insisted this week the Scottish Government was working to a mid-February deadline.

He said discussions have to be concluded by then to give MSPs time to scrutinise and vote on the deal before Parliament is dissolved in March ahead of Holyrood elections.

Chief Secretary to the Treasury Greg Hands has cleared his diary for a full day of talks with Mr Swinney in Edinburgh on Monday.

Speaking ahead of those discussions, a Number 10 spokesman said: "We remain optimistic about reaching an agreement. These talks continue and it's important that we do reach that deal so we can move on. We are making good progress, let's see where we get to."

Asked about the deadline, he said: "The First Minister set out a desire to have this done by Valentine's Day. We have always said 'let's get this done as soon as we can'.

"If we can do it by mid-February, let's do it by mid-February but, ultimately, it is an artificial deadline."

Scottish Secretary David Mundell has already said he "didn't really see the logic" in a February 14 deadline as both Holyrood and Westminster will be in recess.

He also told reporters he did not want to spoil Ms Sturgeon's Valentine's evening with her husband "by phoning up with new proposals".

The Scottish Government has already warned it will pull the plug on the Scotland Bill by recommending a veto in the Scottish Parliament if the two governments cannot strike a deal on the fiscal framework.

SNP ministers insist they are ''not bluffing'' as a bad deal ''would lead to systemic cuts in the Scottish budget, which over a period of a few short years could total hundreds of millions of pounds and, over the longer-term, cost Scotland billions''.

A Scottish Government spokesman said: "We are working to a deadline of February 12 because the Scottish Parliament requested this, as members need time to properly scrutinise and vote on an agreed package before it is dissolved next month ahead of May's election, but ministers will give all the time possible to secure a deal.

"We want to agree a fair fiscal framework and are working to achieve a deal that delivers on the Smith Agreement.

"Ministers have made clear that they will not sign up to any proposed agreement that risks systematically cutting Scotland's budget regardless of anything that this or future Scottish governments do."