The SNP today confirmed it would not back the triggering of formal negotiations to leave the EU if the UK Government calls a parliamentary vote.
A spokesman for the party said its parliamentarians would not support “any proposal that would take Scotland out of the EU”.
The intervention comes after Labour leadership contender Owen Smith pledged to block Article 50 – unless Theresa May promises to put the final Brexit deal, once agreed, to the British people at a second referendum or general election.
When the clause is invoked, the two-year withdrawal negotiation period will start.
Mr Smith – who this week secured the support of Scottish Labour Leader Kezia Dugdale – insisted that Labour would not, on his watch, give the Tories a “blank cheque”.
He added: “The British people were lied to by the Leave campaign – they deserve to have a say on whatever exit deal the Tories strike with the EU.
“Theresa May says that ‘Brexit means Brexit’ – but nobody knows what Brexit looks like.”
In contrast, Labour Leader Jeremy Corbyn said his party will not stand in the way of Brexit, ruling out support for a second referendum on the terms of the UK’s withdrawal.
Asked what the SNP policy would be in the event of a parliamentary vote, a spokesman said: “The SNP is focused on protecting Scotland’s relationship with Europe, in line with the clear wishes of the Scottish people who voted overwhelmingly to remain part of the EU.
“SNP parliamentarians would not vote for any proposal that would take Scotland out of the EU.”
The spokesman did not clarify whether this meant the party would vote against the triggering of Article 50 or simply abstain.
Some 479 MPs – a majority in the Commons – reportedly backed Remain in the EU referendum.
So, if Mrs May puts the question to the house, it could be blocked if enough MPs vote against it.
Responding to Mr Smith, Conservative Party Chairman Patrick McLoughlin, described the referendum result as “clear and decisive”.
The veteran politician, who is to be knighted, said the Tories would “deliver on the people’s verdict”.