London (AFP) - Scottish First Minister Nicola Sturgeon said Saturday her separatist party would make a renewed push to convince Scots of the case for independence from the United Kingdom.

The Scottish National Party leader told the left-wing secessionists' spring conference that a new campaign would attempt to persuade those who were not swayed by the SNP's prospectus for independence 18 months ago.

Scots voted by 55 percent to 45 percent to remain part of the UK in a September 2014 referendum.

"This summer, the SNP will embark on a new initiative to build support for independence," Sturgeon told the conference in Glasgow.

"Our dream is for Scotland to become independent.

"We will achieve independence only when we persuade a majority of our fellow citizens that it is the best future for our country.

"Our success will depend on the strength of our arguments and the clarity of our vision."

The SNP is defending a slim majority in elections to the devolved Scottish Parliament on May 5.

Opinion polls put the nationalists on more than 45 percent, well ahead of Labour on around 20 percent and the Conservatives on around 15 percent.

The new independence campaign "will not be an attempt to browbeat anyone", said Sturgeon.

"Many wanted to be persuaded in 2014 -- but ultimately didn't find our arguments compelling enough.

"Patiently and respectfully, we will seek to convince you that independence really does offer the best future for Scotland.

"That is how we will turn the 45 percent of September 2014 into a strong and positive majority for independence."

Had Scotland voted for independence in 2014, it would now be bankrupt, British business minister Nick Boles has claimed, due to the leave campaign's reliance on the oil price, which has since collapsed.

After the first minister's speech, Scottish Conservative leader Ruth Davidson said: "People voted decisively to remain part of the UK and it's time Nicola Sturgeon respected it."

Sturgeon said in February that if the UK as a whole voted to leave the European Union in the June 23 referendum but a majority of Scots voted to stay, that would "almost certainly" trigger another Scottish independence referendum.

"To take (us) through that exit door against our will would be democratically indefensible," she said Saturday.