The Conservative party is "in chaos" and "showing complete disregard" for the national interest, the First Minister has told STV News.

Attacking its failure to strike a withdrawal deal with the EU, Nicola Sturgeon accused the UK Government of "selfishness" over Brexit.

Her remarks come after a European Council summit in Brussels this week ended with talks between the UK and the EU still deadlocked over the issue of the Irish border.

Theresa May's two-day visit to the summit failed to produce a solution, although the possibility of extending the transition period beyond December 2020 was raised.

If agreed, the change would mean the UK remaining within the single market and customs union and subject to EU rules for almost three years after the official date of Brexit of March 29, 2019.

In Westminster, that suggestion led to open revolt among Brexiteer Tory MPs, including Aberdeen South MP Ross Thomson who said it would leave Scottish fishermen "in a total state of vassalage".

And in Brussels on Friday, Ireland's Taoiseach, Leo Varadkar, warned May that extending the transition was no substitute to agreeing a deal that would prevent border checks with the North.

Speaking to STV News, Sturgeon echoed Varadkar's concerns, saying a longer transition period only makes sense if UK ministers are working towards a clear goal.

She said: "Anybody exercising basic common sense would think that if a deal can be concluded, then more time to put the future relationship in place will be necessary.

"But there's only a point to extending a transition period if the government knows what it is trying to achieve at the end of that.

"And the big problem with the Tory government's position here is they are still fighting among themselves - they have no clear sense of what it is they're trying to achieve."

The First Minister also reiterated the Scottish Government's position that, short of staying in the EU, any Brexit deal should retain the UK's single market and customs union membership.

"I think the sooner common sense prevails on that, the better," Sturgeon added.

"That's the option that resolves the issues around the Irish border; that's the option does the least damage to jobs, living standards and the economy."

The First Minister emphasised the SNP's position that Parliament must get a truly meaningful vote on any Brexit deal May brings back.

It comes amid a growing row at Westminster about whether or not MPs will be allowed to make amendments to the deal, with the Tories resistant.

Sturgeon said: "What cannot be allowed to happen is that the government is able to present this as a choice between the fire and the frying pan, to try to pressure MPs into accepting a bad or blindfold deal because no-deal is worse."

She added: "Any self-respecting House of Commons shouldn't allow the government to restrict its options."

Asked if she believes the Prime Minister would be ousted by her own party, Sturgeon said: "I'll happily leave the future of the Conservative party to the Conservative party.

"They are in chaos. They have shown a selfishness about Brexit and a complete disregard for national interest.

"But what is important now is that people that care about for the future of our economy, our society, for the future of young people, argue that the best option if we're to leave in the EU is to remain in the single market and customs union.

"And if that can't be achieved, then thinking again about membership of the EU is the right thing to do.