Scotland's Brexit minister has said the UK should "commit to a long-term future" in the European single market after Theresa May revealed plans for a two-year transition when Britain leaves the EU.

Michael Russell said that the Prime Minister's "acceptance of a transition period" showed that the UK Government had "changed its position" and urged it to go further.

Earlier on Friday at a landmark speech in Italy, May said neither her government nor the EU would be ready to fully put in place arrangements for Brexit on March 29, 2019 - Britain's slated departure date.

Therefore she proposed a two-year period following that during which "the existing structures of EU rules and regulations" would still apply in Britain.

Addressing EU leaders directly, she said the UK wanted "to be your strongest friend and partner" but later added Britain had "never totally felt at home" within the union.

Responding to her speech, Russell said: "Scotland voted overwhelmingly to remain part of the European Union, and as such the Prime Minister's assertion that the UK 'never totally felt at home' in the EU is not one that chimes with the majority of Scottish opinion.

"Reflecting that public opinion, the Scottish Government believes we should remain in EU.

"If that is not possible, we must remain within the single market and customs union, which is clearly in the best interests of our economy and society."

He added: "While the Prime Minister's speech was short on detail, her acceptance of a transition period within the single market, with freedom of movement, shows that the UK Government has changed its position."

The Brexit minister also said: "Having moved this far, the Prime Minister should now go further and, as we have called for, commit to a long-term future in the single market and customs union, not just as a transition arrangement."

Russell, along with deputy first minister John Swinney, will meet with the UK's first secretary of state Damian Green to further discuss the proposals May outlined.

Scottish Conservative leader Ruth Davidson praised the Prime Minister's speech as "mature and practical" and said it had a lot "for both leavers and remainers".

She added: "A two-year implementation period on the same terms as now gives our businesses the certainty they need to plan."

But Scottish Liberal Democrat leader Willie Rennie accused May of "kicking the can down the road", saying: "Sixteen months on from the Brexit referendum this delinquent Prime Minister is trashing our relationship with Europe.

"She seems incapable of deciding what kind of relationship she wants with Europe and that prolonged uncertainty is causing economic damage."

Rennie's party supports holding a second UK-wide referendum once the final terms of the Brexit deal are known.