A second Scottish independence referendum is now looking inevitable and ministers in the United Kingdom government have now concluded it is a question of when such a vote will be held, the Financial Times reported.

Scottish First Minister Nicola Sturgeon has said that Scotland could hold an independence vote in late 2018, just months before the United Kingdom is due to leave the European Union, though Prime Minister Theresa May has repeatedly said there is no need for such a vote.

"It’s looking inevitable, I don’t think we’re in any position to stop it happening," the FT quoted one unidentified minister close to the discussions as saying.

Another unidentified person briefed on current thinking in PM Theresa May's office said: "The debate is only going to be about the date."

The FT said that the London government would fight to delay the vote until after the exit from the European Union.

The prospect of an independence vote in Scotland that could rip apart the United Kingdom just months before an EU exit would add a tumultuous twist to Brexit with uncertain consequences for the world's fifth largest economy.

The results of the June 23 Brexit referendum called the future of the United Kingdom into question because England and Wales voted to leave the EU but Scotland and Northern Ireland voted to stay.