Scottish National Party leader Nicolas Sturgeon vowed Friday to "escape Brexit" as she launched her independence-seeking, pro-European party's British election campaign.

Scotland's first minister, the top position in its government, said the SNP did not expect to win the December 12 vote.

But Sturgeon said her party "would seek alliances that could keep (UK Prime Minister Boris Johnson's) Conservatives out of power."

"A vote for the SNP... is a vote to escape Brexit," she told a rally in the Scottish capital Edinburgh.

"A vote for the SNP is a vote to take Scotland's future out of the hands of Boris Johnson and a broken Westminster system.

"A vote for the SNP is a vote to put Scotland's future firmly in Scotland's hands."

The SNP, which held 35 out of the 650 seats in the now-disbanded House of Commons, is expected to perform strongly in Scotland.

Sturgeon's plans to hold a second Scottish independence referendum next year are meeting firm resistance from Johnson, who would need to sign off on the poll.

"Absolutely, there is no case" for another independence referendum, Johnson said on a visit to Scotland on Thursday.

Scotland's First Minister, Nicola Sturgeon launches the SNP's election campaign
Scotland's First Minister, Nicola Sturgeon launches the SNP's election campaign AFP / ANDY BUCHANAN

"People were promised in 2014 -- absolutely clearly -- that it would be a once-in-a-generation event."

The 2014 vote in favour of preserving Scotland's place in the UK prevailed by a 55 to 45 percent margin.

But Scotland voted 62-38 percent to remain in the European Union during the 2016 Brexit referendum -- the largest margin of any of the countries comprising the UK.

Some polls suggest that unhappiness with Brexit is boosting support for another independence vote in Scotland.

Johnson's party is expected to suffer losses in Scotland after his Conservative party's popular local leader stepped down this year.

The SNP could turn into a kingmaker should the election results produce a hung parliament.

In contrast to the heads of other pro-EU parties, Sturgeon said she could support the main opposition Labour Party's Jeremy Corbyn as prime minister.

"I like Jeremy Corbyn," she said.

Corbyn has left the door open to a second Scottish referendum but not explicitly supported a 2020 poll.