Ian Blackford said the electorate delivered a “mortal blow” to any thoughts of a hard Brexit in the recent general election and that negotiations should proceed on an all-party basis, with the involvement of devolved administrations.
The election result, which saw the Prime Minister lose her Commons majority, led to speculation that a cross-party approach to Brexit could soften the Government’s approach.
Last week, the Scottish Government’s Brexit Minister Mike Russell called on the UK Government to ‘’reset the process and substance’’ of the negotiation process.
Mr Russell said a blueprint for a softer Brexit already exists in Scotland’s Place In Europe document that the Scottish Government produced in December, including membership of the single market among its proposals.
Speaking a day before talks with the EU begin, Mr Blackford said: “Theresa May asked the electorate to strengthen her hand, but instead they have cut the Tories down to size - voters gave a clear instruction that the Conservatives cannot govern alone and must now reach out to others.
“The Prime Minister must ensure that the Brexit negotiations are representative of all of the UK nations - something which is backed by Scottish business leaders - and that will aim for an outcome which protects Scotland’s interests, particularly our continued place in the Single Market.”
The SNP group leader said the minority government must also change course on austerity.
“Another parliament of Tory cuts is a political choice - not a necessity - and it has been decisively rejected by voters,” Mr Blackford said.
“The SNP has produced credible plans both for dealing with Brexit and an alternative to austerity - protecting our place in the Single Market and protecting public investment in our public services - and the Tory government must now give these plans serious consideration.
“SNP MPs stand ready to work constructively with the UK government to protect Scotland’s jobs, our economy and our public services - but the humbled Tory party must now put country before party and reach out to others.”