Nicola Sturgeon was last night accused of a “reckless pursuit of isolation” following the SNP manifesto launch.
Liberal Democrat Leader Tim Farron also claimed every SNP MP elected on June 8 would be “nothing more than an advocate for independence”.
Conservative sources likewise criticised the “near-identical policies” of the nationalists and Jeremy Corbyn’s Labour.
And Tory party chairman Patrick McLoughlin warned he and the SNP leader were “getting ready to do a deal to prop him up as prime minister in return for a second independence referendum”.
The manifesto, launched in Perth yesterday, says the general election won’t decide whether or not Scotland will be independent.
But it adds: “A vote for the SNP is a vote to reinforce the Scottish Parliament’s right to decide when an independence referendum should happen.
“Last year’s Holyrood election delivered the democratic mandate for an independence referendum. The recent vote of Scotland’s national parliament has underlined that mandate.
“If the SNP wins a majority of Scottish seats in this election, that would complete a triple lock, further reinforcing the democratic mandate which already exists.”
In her speech, Ms Sturgeon told supporters she believed “at the end of the Brexit process”, Scotland must have a choice about its future.
Mr Farron said: “Nicola Sturgeon made it quite clear what people face with the SNP.
“Every SNP MP elected will be nothing more than an advocate for independence.
“In seats right across Scotland it is a straight choice between the independence obsessed SNP and Liberal Democrats.
“June 8 provides a chance to elect an MP that will stand up for their local communities and help change the direction of our country rather than a reckless pursuit of isolation.”
Mr McLoughlin added: “Don’t forget, Corbyn’s own spokesman said ‘Jeremy would definitely talk with the SNP.’
“This manifesto makes clear the price we’d pay for that – higher taxes, more borrowing, weaker defences.”
The Labour leader said yesterday he would allow a second referendum “if the Scottish Parliament and the Scottish people want it” because that is the “whole point” of devolution.
He added that if another poll was to take place it should be after the Brexit negotiations are concluded, but refused to say he would block it if Holyrood passed a motion for one before then.
A Scottish Labour spokesman said: “Labour firmly opposes a second Scottish independence referendum. As our manifesto states, it is unwanted and unnecessary.”