Britain's opposition Labor Party hailed a "seismic" victory in an election for a UK parliamentary seat in Scotland, beating the Scottish National Party (SNP) in a sign of its recovery in the country before a national election expected next year.

Labor is leading Prime Minister Rishi Sunak's Conservative Party in the opinion polls, but will likely need to regain much of the ground lost to the SNP in Scotland over the course of the last decade if it harbors hopes of returning to government after a 13-year absence.

Labor candidate Michael Shanks received 17,845 votes, beating the second-placed SNP candidate Katy Loudon, who got 8,399 votes. There was a swing to Labor from the SNP of 20 percent.

John Curtice, Britain's most prominent pollster, said it was a "remarkable result" for the Labor party, which comes on the eve of its annual conference next week.

"This is the kind of result that suggests that the Labor Party is potentially capable of winning seats again in Scotland," he told BBC News.

Margaret Ferrier was one of a wave of SNP politicians who swept Labor from its one-time Scottish stronghold in 2015.

She tested positive for COVID-19 in September 2020 after speaking in Britain's House of Commons. Instead of isolating as was mandatory at the time, she took a train more than 400 miles back to Scotland.

Ferrier was suspended from her party and had since been sitting as an independent before she was removed by a petition of her constituents in August.

SNP leader Humza Yousaf said it was a "disappointing night," adding that the difficult circumstances of Ferrier's removal.

"We can win this seat back," Yousaf said. "However, we will reflect on what we have to do to regain the trust of the people of Rutherglen & Hamilton West."

Labor lost all but one of its Scottish seats in 2015 to the SNP as it retained support of pro-independence voters in the aftermath of a 2014 referendum where Scots voted to stay part of the United Kingdom by 55 percent to 45 percent.

After Labor retook Rutherglen and Hamilton West with an improved showing in Scotland in 2017, the party again lost all but one Scottish seat in 2019, and the SNP won the seat with a majority of 5,230.

Polls show Labor could draw level with the SNP or even win the most seats in Scotland for the first time since 2010 after the resignation of long-time SNP leader Nicola Sturgeon and a police probe into the party's finances.