The leaders of Scotland's main political parties have clashed over the country's future in both the United Kingdom and Europe.

The day after Prime Minister David Cameron "completely changed" the independence debate in Scotland with his promise of an in/out referendum on the UK's membership of the European Union if the Conservatives win the next general election, the issue dominated heated clashes at Holyrood.

The Labour, Tory and Liberal Democrat leaders all challenged Alex Salmond on the issue at First Minister's Questions.

Opponents of independence have raised doubts over what position Scotland would have in the European Union (EU) if voters chose to leave the UK,

But Mr Salmond insisted the "threat" to Scotland's continued membership of the EU came not from independence, but from the Conservatives, who were "heading towards the exit door".

The SNP leader described the events of the last 24 hours as being "very interesting" in terms of the independence debate.

He told MSPs: "It indicates the threat to Scotland's continued membership of the European Union doesn't come from this Parliament, this Government or the people of Scotland.

"It comes from the banks of the Thames and a Tory coalition Government who are heading towards the exit door and a Labour opposition still to clarify what on earth they think about it."

Labour leader Johann Lamont pressed Mr Salmond on comments made by the Czech Republic's foreign minister, who said that Scotland would get a "worse deal" when negotiating its position within the EU because it was a "much smaller country with much less economic importance".

Meanwhile, Conservative leader Ruth Davidson challenged the First Minister to give the public a say on EU membership in a referendum after independence.

Liberal Democrat leader Willie Rennie said the SNP should agree to work with his party on securing greater powers in a strengthened Scottish Parliament in the UK.

The exchanges also came the day after it emerged Deputy First Minister Nicola Sturgeon's call for early talks with the European Commission (EC) over an independent Scotland's place in the EU had been declined.

But Ms Lamont said the SNP leader had claimed as recently as last week that the Scottish Government was going into talks with EC president Jose Manuel Barroso.

"Can I ask the First Minister when those talks are going to take place?" she demanded.

Ms Lamont claimed her SNP rival had "made the assertion he was going to meet president Barroso before the Deputy First Minister had even received a reply to her letter asking for talks", accusing him of having "just made it up".

She pressed the First Minister on the issue after EC vice-president Maros Sefcovic wrote to Ms Sturgeon saying that president Barroso has not and will not comment on any specific situation relating to any one member state.

Last month, Mr Barroso said it was "obvious" that a newly-independent state would need to apply for membership - a comment widely used to support claims Scotland would not enjoy a smooth transition.

Mr Salmond stressed the EC "haven't expressed an opinion in terms of a specific situation with regards to Scotland".

He argued it would be "would be useful for the European Commission's viewpoint to be heard" on the matter and said the EC would provide an opinion on an independent Scotland's position in the EU if the member state - the UK - asked for this.

"We've made it clear to the UK Government we could go jointly to the European Commission to find out what the view is," Mr Salmond said.

"That seems to be an entirely reasonable suggestion."

Ms Lamont, however, told the First Minister that the Czech foreign minister, Karel Schwarzenberg, had said Scotland would have to apply for EU membership.

She added that Mr Schwarzenberg "went on to say Scotland would get a worse deal because a much smaller country with much less economic importance has less weight".

The Labour leader continued her attack, claiming Mr Salmond and Mr Cameron were "like peas in a pod - they will always put their party interests before the interest of the people of this country".

She also referred to a new poll which showed support for independence had dropped to the lowest level since devolution.

Just 23% want Scotland to leave the UK, the annual Scottish Social Attitudes survey suggested.

Ms Lamont said: "There is nothing quite so negative as trying to mislead the country and perhaps that is why support for independence is at its lowest devolution."

She also claimed Mr Salmond "loves the Tories so much he has taken support for independence down to Tory levels of popularity".

Mr Salmond hit back at the Labour leader's claim he was the like the Tory Prime Minister.

"I'm not the one who's in the Better Together campaign with the Conservative Party," he told her.

Mr Salmond also said the Czech foreign minister had been "specifically asked would he want to block Scotland's entry into the European Union and he said 'no'".

The First Minister added: "If the Czech foreign minister doesn't want to stop Scotland being a member of the European Union, why do the Labour Party seem to cast some doubt on it?"

He insisted: "The proposition that comes forward from the unionist parties that somehow energy-rich, fishing-rich, renewable-rich would not be welcomed with open arms into the European Union is absolutely incredible."

Mr Salmond said that "many, many people across the continent would welcome a pro-European Scotland into the community of nations".

Tory leader Ruth Davidson said there should be another referendum, this time on EU membership, if independence is supported in the vote next year.

Addressing the First Minister, she said: "This week something has become crystal clear: vote for the UK, you have a chance of a say on Europe, vote independence and he's telling you to pipe down and leave it up to him."

She said no-one under 55 is old enough to have voted in the last referendum on the UK's relationship with the rest of Europe.

"We know that this First Minister is old enough to have had his say on Europe decades ago but no-one in Scotland under 55 ever has," she said.

"In this First Minister's world, they never will.

"The First Minister needs to explain to them why he would deny them his say. Can he? Why doesn't he trust them?"

But Mr Salmond said the premise of her question concedes that Scotland will be independent and that the Tories will lose the election.

"Ruth Davidson and her party, if they so wish in May 2016, can go to the Scottish people on their platform heading towards the exit door of the European Union," he said.

"They can have exactly the same position as David Cameron has in 2015."

Scotland would be "safer" under independence, according to Mr Salmond.

He added: "It is obvious to any reasonable person now that the uncertainty on Scotland's position in Europe comes from the Conservative Party led by the nose from eurosceptics and the compromises that David Cameron has had to make to hold onto his job."

Lib Dem leader Willie Rennie called for closer working for a stronger parliament inside the UK.

An independent survey of 1,229 adults over four months last year suggests that support for independence had dropped from a high of 35% in 2005 to 23%.

Support for devolution within the UK was 61% while 63% said the Scottish Parliament ought to have the most influence over the way the country is run.

Mr Rennie said: "I can understand why he might not want to give up on his ambition of an independent Scotland, but can he tell me if Scotland votes No whether he would engage with other parties on further powers for the Scottish Parliament?"

Lib Dems want "home rule" in a federal UK, he said.

Mr Salmond recalled Lib Dem opposition at Holyrood on a coalition with the SNP because they opposed holding an independence referendum.

"Now they are in alliance with the Conservative Party who want a referendum on Europe," he said.

"If the Liberal Democrats are willing to traduce their European principles because they have office in the House of Commons at the present moment, then I don't think that many people will regard them as the most reliable allies in terms of the Scottish self-government cause.

"My proposition to Willie Rennie is, given that in the past at least the Liberal Democrats have expressed the strongest support for Scotland having the strongest possible powers, why doesn't he desert the europhobic Conservatives and the 'no further' Labour Party, and come and join the Yes campaign?"