Theresa May and Nicola Sturgeon at odds over second Scottish independence poll
Nicola Sturgeon and Theresa May have clashed over the prospect of a second Scottish independence referendum following talks about the Brexit timetable.
The First Minister wants to hold another vote on leaving the UK between autumn 2018 and spring 2019, a time scale the Prime Minister is set to reject.
Mrs May has said a referendum during that period would be "unfair" to voters because they would not have all the necessary information to make a choice.
But following a meeting in Glasgow, Ms Sturgeon insisted the Prime Minister had been clear the terms of the UK's divorce from the EU and the details of a new free trade deal would be known within two years.
The Prime Minister will start the Brexit process on Wednesday by triggering Article 50, commencing a two-year countdown to the UK's withdrawal from the European Union.
Meanwhile, Brexit Secretary David Davis has dismissed suggestions the UK could face being forced to pay a £50 billion divorce fee to leave the EU.
Mrs May, who visited Scotland in an attempt to build support across the UK for her Brexit plans, h as insisted it would be "unfair" on the Scottish people to hold another referendum until Brexit has been finalised and the terms of the deal she strikes with Brussels are clear.
But following her talks with the Prime Minister, Ms Sturgeon said it was "very difficult" for her to maintain a "rational opposition" to a referendum on her timetable.
Ms Sturgeon said: "She (Mrs May) is absolutely adamant that she believes the terms of Brexit, by which she means the exit terms, the divorce deal, and the detail of the comprehensive free trade agreement, in other words the future relationship between the UK and the EU, will be clear before the UK exits the EU.
"When I put it to her that what she was suggesting was that in a period of 18 months to two years from now, the terms of the future relationship of the UK and the EU would be clear, she said yes that is what she was saying."
But Mrs May, who used the visit to claim that the four nations of the UK were an "unstoppable force" when they worked together, told reporters her position will not change on Ms Sturgeon's call for a referendum by spring 2019.
The Prime Minister said: '' Now is the time when we should be pulling together, not hanging apart. Pulling together to make sure we get the best possible deal for the whole of the UK.
''Also I think it would be unfair on the people of Scotland to ask them to make a significant decision until all the facts were known, at a point where nobody knows what the situation is going to be."
When talks begin after the Article 50 process starts, the issue of EU negotiator Michel Barnier's demand for a withdrawal fee will be one of the main stumbling blocks.
European Commission president Jean-Claude Juncker has confirmed t he UK's "divorce bill" for Brexit will be around £50 billion.
But on a BBC Question Time Brexit special, Mr Davis said: "The Prime Minister said we are coming to the end of the time when we are paying enormous sums to the EU.
"We will, of course, meet our international obligations but we expect also our rights to be respected too.
"I don't think we are going to be seeing that sort of money change hands."
The Brexit Secretary insisted there were contingency plans in place in case the UK failed to secure a deal on future trading arrangements with the EU but stressed a "comprehensive" agreement remained the Government's goal.
He said the Government's stance that "no deal is better than a bad deal" was in response to talks of "punishment" for the UK in the immediate aftermath of the 2016 referendum.
He dismissed Mr Barnier's warnings the UK would not be able to import nuclear fuel and would face queues of lorries at Dover as trade ground to a halt because of the increased bureaucracy.
"We have got a huge contingency plan exercised across all of these issues, every department of government," he said.
He acknowledged "n o deal is not as easy as some would have you believe" but it would be "a lot better" than critics had claimed.
But he added: "It's not what we want, our aim is a comprehensive free-trade agreement, that's what we are after, because that is much better than anything else."
Mr Davis was challenged about his desire for a trade deal that will provide the "exact same benefits" as membership of the single market and customs union.
"One of the problems that happens when democracies negotiate is that the politicians are afraid of raising expectations," he said.
"The truth is we are negotiating for the future of our country.
"Therefore we want to raise the expectations as much as we possibly can, we want to aim as high as we possibly can.
"I make no apology for being ambitious about what we achieve.
"We are aiming to get the best possible deal with Europe and the best possible deal with the rest of the world.
"That's what this country needs."