Media playback is unsupported on your device Media caption Nicola Sturgeon says she will take steps to ensure the UK government respects her request for a Section 30 order

First Minister Nicola Sturgeon has said there is "no rational reason" for the UK government to block a second Scottish independence referendum.

Ms Sturgeon has written to Prime Minister Theresa May asking for a Section 30 order to allow Holyrood to legislate for a referendum.

The UK government has already said it will not enter talks about a new vote.

Ms Sturgeon said she would come back to Holyrood in the coming weeks to update MSPs on how she would "move forward".

MSPs voted by 69 to 59 to mandate the Edinburgh government to open talks with its London counterpart over an independence vote.

Citing that 62% of those who voted in Scotland in the EU referendum had backed Remain, Ms Sturgeon argues that the country being taken out of the EU and the single market is "clearly against the will of the majority of people who live here".

Downing Street confirmed that the letter was received by email, and said a response would be sent in due course.

However, Mrs May has repeatedly said "now is not the time" for a new vote, arguing that all focus should be on the Brexit talks and saying a referendum in the short-term would not be fair on Scottish voters.

Ms Sturgeon, who has previously said she suspects the UK government may use Brexit as a "power grab", said that refusing permission for a vote would "go against the very foundations of devolution".

Media playback is unsupported on your device Media caption Theresa May refuses to be drawn on the "principle" of a second independence referendum

In her letter to the prime minister, Ms Sturgeon said the voices of devolved administrations had been "largely ignored" so far in the Brexit process, adding that "all attempts at compromise" had been "rejected, in most cases with no prior consultation".

She said the two sides were in agreement about the timetable of the Brexit negotiations over the next two years, adding that there was "clear precedent" in the 2012 Edinburgh Agreement, which gave permission for the 2014 referendum.

She said: "There appears to be no rational reason for you to stand in the way of the will of the Scottish Parliament and I hope you will not do so.

"However, in anticipation of your refusal to enter into discussions at this stage, it is important for me to be clear about my position.

"It is my firm view that the mandate of the Scottish Parliament must be respected and progressed. The question is not if, but how.

"I hope that will be by constructive discussion between our governments. However, if that is not yet possible, I will set out to the Scottish Parliament the steps I intend to take to ensure that progress is made towards a referendum."

'Crucial decision'

A spokesman for the UK government said: "The prime minister has been clear that now is not the time for a second independence referendum, and we will not be entering into negotiations on the Scottish Government's proposal.

"At this point, all our focus should be on our negotiations with the European Union, making sure we get the right deal for the whole of the UK.

"It would be unfair to the people of Scotland to ask them to make a crucial decision without the necessary information about our future relationship with Europe, or what an independent Scotland would look like."

Scottish Secretary David Mundell said the UK government "won't be entering into any negotiations at all until the Brexit process is complete".

He added: "We don't have a crystal ball as to how long that process will take. We don't recognise, for example, 18 months as being a key point in the journey.

"It will be a journey that will involve the negotiations with the EU, it may be a journey that involves transitional measures, it may be a journey that involves significant implementation time."