Image caption First Minister Nicola Sturgeon held an event with the SNP's MPs outside Westminster ahead of the vote

SNP MPs will abstain in the House of Commons vote on whether there should be a snap general election, the party's leader at Westminster has confirmed.

Angus Robertson said his party believed in fixed-term parliaments, but would not stand in the way of an early election.

The prime minister's plan to hold an election on 8 June is expected to be authorised by MPs later.

Labour and the Liberal Democrats have already said they support the move.

The next general election had been due to be held in 2020, but the Fixed Term Parliaments Act allows for one to be held earlier if two-thirds of MPs are in favour.

Theresa May has argued that a snap general election will help the UK make a success of Brexit and provide long-term certainty.

Opposition parties have highlighted Mrs May's U-turn after she had previously insisted she would not be calling an early poll.

But the prime minister told the BBC she had "reluctantly" changed her mind on the issue in recent weeks.

Asking the public to trust her, she said a new mandate would give her the "strongest hand" in talks and make it hard for people to "frustrate" EU exit.

Image copyright Getty Images Image caption Theresa May has urged Scottish voters to use the election to reject the SNP's calls for an independence referendum

Speaking on the BBC's Good Morning Scotland programme, Mr Robertson accused the prime minister of putting her party before her country by holding a general election just two years after the last one.

He added: "We are supporters of the Fixed Term Parliament Act, and that means that parliaments should go their term.

"But we are not going to stand in the way of the election because the election is going to happen.

"The Labour Party is going to vote with the Tories. We are not going to vote with the Tories, we are not going to make life easy for them, we are here to hold them to account."

The decision to abstain in the Commons vote was made at a meeting of SNP MPs on Tuesday evening.

Mr Robertson insisted he "absolutely" relished the prospect of an election, and said the SNP would be contesting every seat in Scotland with the intention of winning them.

He said the vote "will be an opportunity for us in Scotland to at least get some insurance against the worst excesses of a hard-right Brexit, which is what the UK government is steering towards".

Mr Robertson also confirmed that the SNP winning a majority of seats in Scotland would not be enough for the country to become independent - with a referendum needed to decide the issue.

But he would not confirm whether or not the party's manifesto would have a commitment to an independent Scotland seeking EU membership - which is the SNP's current policy.

'Crumble to dust'

First Minister and SNP leader Nicola Sturgeon joined Mr Robertson and the party's other MPs outside Westminster ahead of the Commons vote.

She told journalists that the UK government's arguments against holding a second independence referendum would "crumble to dust" if the SNP won the election in Scotland.

The SNP won 56 of the country's 59 seats in 2015 - making it the third largest party in the Commons - with the Conservatives, Labour and Liberal Democrats winning one each.

But two MPs - Michelle Thomson and Natalie McGarry - are currently suspended by the party.

Ms McGarry has been charged with fraud offences relating to a potential financial discrepancy in the accounts of the Women for Independence group, while Mrs Thomson has been reported to prosecutors after a police investigation into allegations of mortgage fraud.

The SNP's National Executive Committee will meet on Saturday to discuss whether Ms McGarry and Mrs Thomson would be able to put themselves forward as potential candidates in the election.

Image copyright PA Image caption The prime minister is expected to win the backing of the required two-thirds of MPs

Recent opinion polls have suggested that the SNP continues to hold a commanding lead over its rivals in Scotland, with the Conservatives in second place ahead of Labour.

Writing in the Scotsman newspaper on Wednesday morning, the prime minister said that backing the Scottish Conservatives in the election would send a clear message of opposition to SNP calls for a second independence referendum.

And she insisted that holding an election now will provide the UK with "five years of strong and stable leadership to see us through the (Brexit) negotiations and the period thereafter".

Mrs May added: "A vote for the Scottish Conservatives in June will do two things. It will send a clear message of opposition to the SNP's divisive plans for a second independence referendum, and it will strengthen my hand as I negotiate on behalf of the whole United Kingdom with the EU.

"In Scotland, only Ruth Davidson and her Scottish Conservative colleagues are able to stand up for our United Kingdom and provide a strong voice against the SNP.

"And only a strong Conservative Government at Westminster can deliver a Brexit that works for the whole UK."

'Historic choice'

Meanwhile, Scottish Secretary David Mundell insisted it was "absolutely" not hypocritical of the UK government to call a snap general election while denying SNP calls for a second referendum on independence.

He said the general election would be over in six weeks, before Brexit negotiations begin, while Ms Sturgeon wanted the independence referendum campaign to be held while the EU negotiations were ongoing.

Scottish Labour leader Kezia Dugdale said the upcoming general election would give voters a "significant and historic choice".

She said: "At this election, the choice again will be clear: a Tory Party intent on a hard and damaging Brexit; or a Labour Party that will oppose a second independence referendum and fight for a better future for everybody.

"We will work tirelessly to elect Jeremy Corbyn Prime Minister and deliver a Labour government."

Scottish Liberal Democrat leader Willie Rennie also said his party was "relishing the prospect of this election".

He stated: "It is a chance to change the direction of the whole of the UK. Our optimistic agenda is pro-UK, pro-EU and progressive. We stand with the majority opinion in this country."

And Scottish Greens co-convener Patrick Harvie urged Scottish voters to use the election to "reassert our choice for a fairer and more equal society."