The pound was poised to end the week on a losing note, as it hit a fresh one-week low against the euro after Northern Ireland's High Court rejected a legal bid to secure a parliamentary vote on Theresa May's Brexit plans.

Sterling had hit a one-week high of $1.2271 on Thursday (27 October), after official data showed the economy grew more than expected in the three months after the European Union referendum but quickly relinquished the gains.

By early afternoon on Friday, the UK currency was 0.29% lower against the greenback at $1.2124 and was 0.49% lower against the euro, exchanging hands at €1.1103, the weakest level in a week. Having failed to capitalise on better-than-expected GDP data, analysts warned that the pound could weaken even further next year.

"The pound touched 31-year lows against the dollar in 2016, and may be poised to continue lower in 2017 as the US dollar responds to higher interest rates," said Evdokia Pitsillidou, risk management associate at easyMarkets.

The most recent losses came after the Northern Ireland high court ruled against campaigners, who had argued that Westminster could not begin the formal legal process for leaving the EU without a parliamentary vote. Implementing the royal prerogative to trigger Article 50, they claimed, would breach Northern Irish law.

Elsewhere, the euro was 0.19% higher against the dollar, fetching $1.0918 but the greenback was firmly on the front foot against its other major rivals, after data showed the US economy grew at the fastest pace in two and a half years in the third quarter.

Boosted by surge in export, GDP in the US expanded 2.9% year-on-year in the three months to September, dwarfing the 1.4% rate recorded in the previous quarter. Coupled with a solid pace of hiring, the latest GDP figures strengthened the case for the Federal Reserve to raise interest rates in December, which in turn boosted the dollar.

The greenback was 0.16% and 0.25% respectively against its Canadian and Australian counterparts, trading at CAD$ 1.3407 and AUD$1.3208 and edged 0.06% higher against the yen, to fetch ¥105.35.

"The news of a decent acceleration in GDP growth to well above its potential will leave Fed officials a lot more confident about the outlook,"said Paul Ashworth, chief US economist at Capital Economics, "a rate hike is on the way."