The Prime Minister's opposition to a second independence referendum will "crumble to dust" if the SNP beat the Conservatives in Scotland at the general election, the First Minister has said.

Nicola Sturgeon made the comments outside Westminster with her party's 54 MPs.

It comes after Scottish Conservative leader Ruth Davidson said her party is "optimistic" about gaining more seats.

The Conservatives polled 14.95% of the vote in Scotland at the last general election in 2015 but managed to win only one seat.

Sturgeon said her party was "raring to go" after May announced on Tuesday she intended to hold a snap election on June 8.

The SNP leader said: "It is a vote to ensure that the future of Scotland is decided not here at Westminster but in Scotland by the people of Scotland.

"And make no mistake, if the SNP wins the election in Scotland and the Tories don't then Theresa May's attempt to block our mandate to give the people of Scotland a choice over their future when the time is right will crumble to dust."

Sturgeon said her party is "determined that Scotland's voice will be heard and heard loudly and clearly" at Westminster.

Scottish Conservative leader Ruth Davidson said: "Nicola Sturgeon has today made it clear: at this election, we face the grave danger of a weak Labour-SNP-Lib Dem alliance, headed by Jeremy Corbyn, plunging the UK into more instability and uncertainty.

"We know Jeremy Corbyn is 'absolutely fine' with the SNP's demand for an immediate second referendum.

"There is therefore a real danger of Mr Corbyn and Ms Sturgeon cooking up a deal to suit both their purposes.

She continued: "The truth is that it's only the Scottish Conservatives at this election who can be trusted to stand up for our Union, and work to get the best Brexit deal for all of us.

"For MPs like Angus Robertson and Pete Wishart, these comments will be as welcome as a hole in the head.

"They must now explain to their constituents why they think Jeremy Corbyn is the best person to become Prime Minister at this election, and why he is best placed to lead us through Brexit."