NICOLA Sturgeon has said an admission by Theresa May that the UK faces tough times as it leaves the EU is fresh evidence the Tories “put Scotland’s economic interests on the line” by calling an In-Out referendum.

In a stark admission, the Prime Minister said Britain needed to be prepared for some “difficult times” as it pulls out of the the European Union and warned that Brexit would not be “plain sailing”.

In a further blow, US President Barack Obama said his country would prioritise trade negotiations with the EU and Pacific nations over deals with the UK.

A spokesperson for Sturgeon suggested May’s comments set out the bleak impact of Brexit on jobs, living standards and prosperity in Scotland, which decisively backed Remain but was outvoted by the UK as a whole on 23 June.

May, in her first major interview since becoming Prime Minister, said formal EU talks would not begin until 2017, but vowed the process would not be “kicked into the long grass”.

However, Former Tory leader and arch Eurosceptic Iain Duncan Smith said the UK could trigger the formal process to leave the EU before Christmas and insisted it was a “ridiculous pipe dream” to suggest Brexit would not happen.

He said: “The truth is we’re leaving, the British people voted for this and as a democrat you have to stand by what they voted.

“As Theresa May made clear from the Cabinet meeting the other day ... the migration process is about taking control of your borders, control of your laws which allows you to set your overseas treaties.”

Speaking to Pienaar’s Politics on BBC Radio 5 Live, he added: “I’d expect Article 50, as our international legal obligation, to be invoked fairly soon – I’d think if not before Christmas, fairly soon afterwards.”

May said she would not pretend that leaving the EU would be straightforward, despite what she claimed were positive economic figures in the UK since the referendum in June.

She said: “We have had some good figures, and better figures than some had predicted would be the case. I’m not going to pretend that it’s all going to be plain sailing. I think we must be prepared for the fact that there may be some difficult times ahead. But what I am is optimistic.”

When asked about Scottish independence, May questioned whether voters in Scotland supported the prospect of a second referendum on leaving the UK. “I think if you look at some of the results that are now coming out of polling in Scotland, they suggest that the Scottish people don’t want there to be a second referendum,” she said.

May added that the Scottish government would be “fully involved” and “fully engaged” in the Brexit discussions.

However, Sturgeon’s spokesperson said the UK Government could not block an independence referendum if Holyrood felt it was the only way to secure Scotland’s interests – a position the FM claimed was accepted by Scottish Tory leader Ruth Davidson.

The Scottish Government yesterday challenged the PM to set out how she would safeguard Scotland’s interests during the Brexit process.

Sturgeon’s spokesperson said: “This eventual admission by the Prime Minister proves the very simple fact that it is the Tories who have put Scotland’s economic interests on the line through a Brexit referendum that threatens to take us out of the EU against the will of the people of Scotland. The Prime Minister came to Scotland in July and gave a very clear undertaking that she is prepared to consider the options that the Scottish Government puts forward to protect Scotland’s interests.

“The onus is very much on the Tory Westminster government to show they are serious about engaging positively with a view to safeguarding Scotland’s interests.

“The people of Scotland will now be watching carefully to see if it is possible for Scotland’s vital interests to be protected through the UK or are the Tories, through their actions and behaviour, determined to demonstrate that they cannot? Just as Ruth Davidson conceded on the BBC Sunday Politics in July, it would be wrong for the UK Government to seek to block a referendum if the Scottish Parliament decided it was the best or only way to protect Scotland’s interests.”

Following talks between May and Obama at the G20 summit in China, the US President asserted that the “special relationship” between the US and UK was still strong despite the Brexit vote. He played down his suggestion that Britain would have to join the “back of the queue” over trade, but emphasised that EU deals would take priority.

Meanwhile, Scottish Tory leader Davidson faced a fresh call to apologise over the conduct of Aberdeenshire West MSP Alexander Burnett.

Burnett was accused by the French-born former SNP MSP Christian Allard of failing to properly declare his financial interests in a property company while asking five questions about a housing development by a rival firm in his constituency.

In response, the Scottish Conservatives issued a press release that stated: “Some people may find it bizarre that an EU citizen has an interest in a planning application in Banchory.”

Last night, SNP MSP Gillian Martin said: “Regardless of where blame lies, Ms Davidson should get her house in order, withdraw the comment and apologise for this xenophobic nonsense.”