LONDON - Scottish First Minister Nicola Sturgeon on Tuesday said she was nearly ready to give more details on how the nation's devolved parliament could move ahead with a new independence referendum without the consent of the British government.

British Prime Minister Boris Johnson and his Conservative Party, which is in opposition in Scotland, strongly oppose a referendum, saying the issue was settled in 2014 when Scots voted against independence by 55% to 45%.

But pro-independence parties won a majority in the Scottish parliament in an election held last year, which Sturgeon said gave her an "indisputable democratic mandate" to push ahead with plans for a second referendum.

Sturgeon, leader of the pro-independence Scottish National Party (SNP), is aiming to hold a vote by the end of 2023 even though British Prime Minister Boris Johnson has refused to issue a "Section 30" order to allow one.

"If we are to uphold democracy here in Scotland, we must forge a way forward, if necessary without a Section 30 order... However, we must do so in a lawful manner," Sturgeon said in a speech.

She said work was underway on how to proceed, given the British government contests that the Scottish parliament has the power to grant such a vote.

"I do plan to give a significant update to parliament very soon indeed," she said.

Johnson's spokesman said the British government's position had not changed.

"It's not something the Prime Minister believes the public want either government to be focused on at a time when there are significant challenges affecting them right now," the spokesman said.

Sturgeon, a scathing critic of Johnson and Brexit, was speaking at the launch the first of several policy papers making the case for independence.

She argued that Scotland was similarly sized to several other European countries that were fairer and wealthier than Britain.

"Scotland under Westminster control is being held back," Sturgeon said. "With independence, we too would have the levers and the autonomy that these countries take for granted to help fulfil their potential."

(Reporting by Alistair Smout; editing by William James and Alex Richardson)