Theresa May has rejected calls from Nicola Sturgeon for a second independence referendum.
The Prime Minister said on Thursday that "now is not the time" for another referendum, two and a half years after the last independence vote.
First Minister Nicola Sturgeon has labelled Downing Street's stance as a "democratic outrage".
May said holding another referendum would make it "more difficult" to get the "right deal" for the UK and Scotland in Brexit.
The Prime Minister stated: "To be talking about an independence referendum would make it more difficult for us to get the right deal for Scotland and the right deal for the UK.
"I think it wouldn't be fair to the people of Scotland who'd be asked to make a crucial decision without the necessary information, knowing what the future partnership would be or what the alternative of an independent Scotland would look like.
"Right now we should be working together, not pulling apart. We should be working together to get that right deal for Scotland, that right deal for the UK as I say that's my job as Prime Minister and so for that reason I say to the SNP: now is not the time."
She added: "I'm responding to the proposal that's been put forward by the First Minister. I say now is not the time and the reason I say that is because all our energies should be going into negotiations with the European Union to make sure we get the right deal."
She would not be drawn on what the right timescale would be for a second independence referendum in an interview on Thursday.
It comes after Sturgeon said earlier this week that indyref2 should be held between autumn 2018 and spring 2019 as the UK Government prepares to trigger Article 50 to begin the formal process of exiting the European Union.
Next week, MSPs are due to debate a request for a Section 30 order to transfer power for the vote to the Scottish Parliament.
The First Minister indicated there was little chance of a compromise with the UK Government on the issue of Scotland having a special deal to stay in the European single market.
After the Prime Minister's interview on Thursday, Sturgeon responded: "I'm not proposing another referendum now, I'm proposing a referendum when the terms of Brexit are clear but before it is too late for Scotland to choose a different path.
"If that is what the Scottish Parliament votes for, when it has the opportunity next week, then I think the Prime Minister should respect the will of the Scottish Parliament."
When pressed further on May's comments about not being willing to discuss this further, Sturgeon told STV's Colin Mackay: "I've made my views very clear."
In a statement released later on Thursday, the First Minister said it would be a "democratic outrage" for UK Government to block a referendum if MSPs back it.
Sturgeon said: "As I set out earlier this week, we are not proposing a referendum now - we are proposing to give the people of Scotland a choice once Brexit is clear but before it is too late. "The PM does not appear to have listened to our proposal.
"We will put our proposition, based firmly on this government's democratic mandate, to the Scottish Parliament next week, and then we will put our formal proposals to the UK Government.
"If the Prime Minister refuses to engage on the terms of a referendum before Brexit takes place then she is effectively trying to block the people of Scotland having a choice over their future. That would be a democratic outrage.
"It is for the Scottish Parliament - not Downing Street - to determine the timing of a referendum, and the decision of the Scottish Parliament must be respected.
She added: "It would be outrageous for the Scottish Parliament to be frozen out of the process.
"The Scottish Government has a cast-iron democratic mandate to offer people a choice and that mandate must be fulfilled.
"Any bid by the UK Government to block the people of Scotland from making a choice will be untenable, undemocratic and totally unsustainable - and clearly shows that the UK Government recognises it is out of step with the Scottish people."