The Prime Minister called an early general election before "criminal prosecutions for alleged expenses fraud" against sitting Conservative MPs, the First Minister has claimed.

The Crown Prosecution Service is currently considering police reports from 12 forces in England on alleged misreporting of election spending by up to 20 Conservative MPs in the last election.

Theresa May announced plans last week to hold a snap election on June 8 after repeatedly saying for months she had no intention of doing so.

MPs backed her plans in a Commons vote on Wednesday.

The SNP leader said May's decision to do so was partly due to possible prosecutions against these 20 MPs.

In a speech at the Scottish Trades Union Congress conference, she said: "We are, of course, at the start of a general election campaign.

"A campaign called by the Prime Minister last week for one purpose and one purpose only: to strengthen the grip of the Tory party and crush dissent and opposition, and to do so before possible criminal prosecutions for alleged expenses fraud at the last general election catch up with her.

"Whatever else happens in this election, we should not allow the Tory party to escape the accountability for any misdemeanours that may have led to them buying the last general election."

Sturgeon said the election was a change for Scotland to reject the Conservatives.

She added: "That's why the next few weeks and the next two years as the Brexit process completes will be so important for our future.

"Indeed, faced with the prospect of a Prime Minister who, in her own words, wants to strengthen her own hand to deliver the kind of Brexit that she wants, it's more important than ever that we have strong voices in Westminster and then, once the terms of Brexit are clear, the people of Scotland, not the Tory party, should have a choice about our own future."

The Scottish Conservatives said the SNP wants to use the general election as a way of showing support for independence.

Douglas Ross MSP said: "There is one cast-iron rule about the SNP - whenever it says something has got nothing to do with independence, it's a sure-fire way of knowing it has everything to do with independence.

"Just like she did in the after the Brexit vote last year, Nicola Sturgeon wants to try to use this election to boost her flagging case for a referendum. Everybody knows that.

"The only way to send them a message is to back a Scottish Conservative party which is utterly committed to stopping a divisive second referendum in its tracks."