By Tom Gordon and Kate Devlin 

THERESA May has undermined her own “now is not the time” argument against a second referendum by calling a snap election, Nicola Sturgeon said yesterday.

The First Minister’s office said the Prime Minister had “shot her own fox” by taking time out from Brexit - the same reason she cited against holding a new independence vote.

The SNP also said that if Mrs May could change her mind on something as big as a general election, after previously ruling one out, she could flip-flop on a referendum too.

SNP Westminster leader Angus Roberston said Mrs May's decision to hold an election while stonewalling a Scottish referendum was a “screeching U-turn”.

Ms Sturgeon accused Mrs May of making a “huge political miscalculation”, saying the election would give Scots a chance to “reinforce” the SNP’s mandate for another referendum.

The First Minister said: “This announcement is one of the most extraordinary U-turns in recent political history, and it shows that Theresa May is once again putting the interests of her party ahead of those of the country.

“She is clearly betting that the Tories can win a bigger majority in England given the utter disarray in the Labour Party.

“That makes it all the important that Scotland is protected from a Tory Party which now sees the chance of grabbing control of government for many years to come and moving the UK further to the right – forcing through a hard Brexit and imposing deeper cuts in the process.

“That means that this will be – more than ever before – an election about standing up for Scotland, in the face of a right-wing, austerity obsessed Tory government with no mandate in Scotland but which now thinks it can do whatever it wants and get away with it.”

The SNP won 56 of 59 Scottish seats at the last Westminster election, but has suspended two of its MPs - Natalie McGarry in Glasgow East and Michelle Thomson in Edinburgh West - because of police and Crown Office enquiries, and the pair currently sit as Independents.

If their suspensions remain in place, they would be ineligible to stand for the SNP in June.

Asked by the BBC about the pair’s status, Ms Sturgeon said: “The SNP’s national executive committee will meet over the next few days to set out the terms of candidate selection, and these matters - as well as a number of other matters - will be discussed in the proper way.”

Asked later if the First Minister believed Mrs May’s insistence “now is not the time” mantra had been undermined by her call for an election, the First Minister’s spokeswoman said: “The Prime Minister might reflect on what now is the time for.

“If it’s not the time for another referendum, how is it time for another election?

“She has shot her fox with that one. She has clearly done this for party political reasons.”

The election announcement temporarily derailed Ms Sturgeon’s plan to tell MSPs her “next steps” to hold a referendum in the teeth of Westminster opposition.

The First Minister had been expected to make a statement to Holyrood in the coming weeks, but this has now been put off, probably until after the election, as there will be no UK government to interact with or put pressure on.

However her spokeswoman insisted it remained the Scottish Government’s intention to hold a referendum in late 2018 or early 2019 to let voters choose between Brexit and independence.

She said: “Those plans remain the same. The mandate for the referendum is a mandate from the Holyrood elections and the mandate that we got from the Scottish Parliament before the Easter recess. We will set out the next steps in due course.

“Those next steps will take light of the fact that an election has been called, and that may affect the timing.. . in a short term sense. There won’t be a UK Government to deal with so we obviously have to take account of that in our planning.”

With the SNP facing an uphill struggle to repeat its 56-seat haul, Westminster leader Angus Roberston downplayed the significance of losing seats.

He said that “no doubt” other parties would suggest Scots were less convinced about the SNP if the party lost a couple of seats, but said it would not undermine the campaign for another independence referendum.

He said: “More neutral observers, even centre right commentators… are suggesting that (if) the SNP still won a clear majority of seats in Scotland (the party) would not be undermined.”

He added that the party intended to contest every seat in Scotland “and we will be trying to win in every single seat in Scotland”.

But he would not be drawn on what the SNP’s manifesto would say on European Union membership.

He said: “The policy for the SNP is as it was. Issues in relation to the manifesto for the snap general election will become clear when the SNP has written and presented that manifesto”.

He added: “The SNP’s policy is to remain a member of the European Union”.