Prime Minister Theresa May has triggered Article 50 of the Lisbon Treaty to start the country's exit from the European Union.

The notification letter, which was delivered to the EU by the British ambassador Sir Tim Barrow, outlined the UK Government's approach and aims to the Brexit negotiations.

The UK and the other 27 member states of the EU now have two years to draft an exit deal.

May told MPs that Holyrood will see a "significant increase" in its powers and that no decisions taken by the Scottish Government, and the other devolved administrations, will be removed from them.

First Minister Nicola Sturgeon described today as a "leap in the dark".

The Prime Minister addressed the House of Commons minutes after Sir Tim handed the letter to the European Union.

She told MPs: "We will strengthen the Union of the four nations that comprise our United Kingdom.

"We will negotiate as one United Kingdom, taking account of the specific interests of every nation and region of the UK and when it comes to the powers that we will take back from Europe, we will consult fully on which powers should reside in Westminster and which should be passed on to the devolved administrations.

"But Mr Speaker, no decisions currently taken by the devolved administrations will be removed from them. And it is the expectation of the government that the devolved administrations in Scotland, Wales and Northern Ireland will see a significant increase in their decision-making power as a result of this process."

European Council president, Donald Tusk, who received the letter tweeted: "After nine months the UK has delivered."

The UK as whole voted to leave the organisation in June last year by a margin of 52% to 48%.

The result was not replicated in Scotland with voters here backing staying in by 62% to 38%.

The start of the withdrawal process comes a day after a majority of MSPs voted to hold a referendum between autumn next year and spring 2018.

In response to the triggering, Nicola Sturgeon said: "Today's triggering of Article 50 represents a leap in the dark by the Prime Minister.

"Fully nine months after the EU referendum, the UK Government still cannot answer basic questions about what Brexit will mean for businesses, for the economy generally and for the type of society we live in.

"I wish the Prime Minister well in the negotiations which lie ahead, because a good Brexit deal for the UK is in Scotland's interests.

She continued: "But the UK Government's hard-line approach to Brexit is a reckless gamble, and it is clear, even at these very early stages, that the final deal is almost certain to be worse economically than the existing arrangements - and potentially much worse.

"Scotland voted decisively to remain part of Europe, but the UK Government only formally responded with a dismissal of our compromise proposals to keep Scotland in the Single Market at the same time as the Article 50 letter was sent.

"The next two years are hugely important and will determine the kind of country Scotland will become.

"The Prime Minister has today confirmed her aim is to reach a Brexit agreement covering a future relationship within two years.

"So the people of Scotland must have the final say on their own future once the terms of Brexit are clear."

The Scottish Government believe independence is the only way to protect the country's relationship with the rest of Europe after Downing Street did not take on board its proposal to keep Scotland inside the single market even if the rest of the UK leaves.

Later this week, First Minister Nicola Sturgeon will contact the Prime Minister and request a section 30 order - the legal instrument to devolve the power to hold a referendum - to empower Holyrood.

May, however, said "now is not the time" for a fresh poll on the independence question.

Following the vote at the Scottish Parliament, the UK Government said it "will not be entering into negotiations on the Scottish Government's proposal".

Sturgeon told MSPs on Tuesday she will return to Holyrood after the Easter recess to update them on what she intends to do if Downing Street continues to refuse to enter into talks over a referendum.