Nicola Sturgeon has said the European election is an opportunity for Scottish voters to tell Theresa May they don't want Brexit.

Launching the SNP's campaign at Edinburgh's Dynamic Earth, the First Minister said: "Scotland has had enough of being ignored."

Sturgeon described the vote in two weeks' time as "the most important European election in Scotland's history".

The Scottish Liberal Democrats also fired the starting gun on their campaign in the capital on Thursday, with party leader Willie Rennie saying the public is "fed up of Brexit".

He called on voters to back the Lib Dems on May 23 to "prove the UK is an outward-looking country and remain in the EU".

Meanwhile, Ukip Scotland got campaigning under way with the publication of its manifesto, which calls for a no-deal Brexit and pledges Ukip MEPs to vote against all EU legislation.

The party's lead candidate told STV News there is "no alternative" to no-deal if voters want to avoid a "fudged Brexit".

It comes on the day 750,000 postal ballots were sent out to Scots - around one in five voters - ahead of a fortnight of campaigning.

The First Minister said the SNP's campaign would be one of hope and ambition "for the positive role Scotland can play in Europe and the wider world".

She said: "This is by far the most important European election in Scotland's history.

"At stake in this election is not just which parties and which candidates will be elected to the European Parliament.

"At stake also is whether Scotland can remain inside the European Union at all.

"On May 23 by voting SNP, people in Scotland can send a clear and unequivocal message to Theresa May.

"That message is this: Scotland has had enough of being ignored."

Responding to Sturgeon's campaign launch speech, Scottish Conservative deputy leader Jackson Carlaw said she had "never met a referendum result she accepts".

Earlier in Edinburgh, the Scottish Lib Dems launched their campaign at a local fishmonger's.

"People are fed up with Brexit," leader Willie Rennie said. "It has caused division in our country and damaged our economy."

He added: "Our economy is in jeopardy. Business needs to trade without new barriers, Airbus is already leaving and farmers can't get the seasonal workers they need.

"Our public services are under threat. Hundreds of thousands of EU nationals live in Scotland. We rely on them to staff our hospitals and schools and we want them to feel welcome here.

"Finally our security is at risk. Our police need to work with European police forces. We can't risk peace in Northern Ireland and we want to work with the whole of Europe to keep us safe from climate change.

"A vote for the Liberal Democrats is a positive vote to solve these problems, prove the UK is an outward-looking country and remain in the EU."

Elsewhere, Ukip Scotland's lead candidate Donald MacKay said the UK should decide what Brexit looks like, not the EU.

Speaking to STV News, he said "there is no alternative" to a no-deal, adding: "Anything that involves a deal is arguably not Brexit at all, that's the point.

"We are perfectly capable of forming deals with other trading blocs in the world and with the EU itself.

"We'll decide what deals we want - trading arrangements, tariff agreements, we'll decide. The House of Commons will decide, the Cabinet will decide.

"If we're going to have 'deals', then they're telling us the circumstances in which we should leave and some of us believe that's not Brexit at all.

"So we want a proper Brexit as opposed to a fudged Brexit or a soft Brexit."

The Scottish Greens launched their manifesto on Tuesday, while the Scottish Tories, Scottish Labour and Nigel Farage's Brexit Party will hold events in Scotland next week.

Change UK is expected to hold a rally north of the border on the weekend before the election.