Britain's Rishi Sunak said he would meet King Charles to formally resign as prime minister on Friday and would also stand down as leader of the defeated Conservative Party after Keir Starmer's Labour Party won a landslide election victory.

"I have given this job my all, but you have sent a clear signal that the government of the United Kingdom must change, and yours is the only judgment that matters," Sunak said in a speech to voters outside the prime minister's office in Downing Street.

"I have heard your anger, your disappointment and I take responsibility for this loss. To all the Conservative candidates and campaigners who worked tirelessly, but without success, I'm sorry that we could not deliver what your efforts deserved."

Donald Trump has congratulated his right-wing ally Nigel Farage after he won his first seat in UK’s parliament following seven failed attempts.

Farage’s right-wing Reform UK party cinched four seats as its hardline immigration policies appeared to steal votes away from Conservatives.

Trump took to his Truth Social platform to congratulate his old friend.

"Congratulations to Nigel Farage on his big WIN of a Parliament Seat Amid Reform UK Election Success,” he wrote. "Nigel is a man who truly loves his country!" he added.

The likely Republican nominee for this year's US election did not mention the Labour landslide victory or outgoing prime minister Rishi Sunak.

Britain's outgoing Prime Minister Rishi Sunak will make a statement in Downing Street at around 0930 GMT before meeting with King Charles to formally resign, his office said on Friday after the opposition Labour Party won a landslide election victory.

The newly elected Labour Prime Minister Keir Starmer will then meet with Charles at Buckingham Palace before making a speech in Downing Street at around 1120 GMT, the statement added.

Former British prime minister Liz Truss, who became the country's shortest-serving leader ever when she sparked a bond market meltdown and a collapse in sterling, lost her parliamentary seat in the election on Friday.

Truss secured 11,217 votes in her South West Norfolk constituency in eastern England, behind 11,847 votes for Labour candidate Terry Jermy.

Taking over from the scandal-ridden premiership of Boris Johnson, Truss, 48, was forced to announce her resignation after just 44 days when her unfunded tax cuts sparked financial market turmoil, raising the cost of mortgages for homeowners already in the middle of a cost-of-living crisis.

Lampooned in the media - one tabloid newspaper asked in the dying days of her premiership whether she would last longer than a supermarket lettuce - Truss had become synonymous for many voters with the chaos and failures of Conservative government.

She has, however, remained an influential voice among right-wing lawmakers in the party.

Australian Prime Minister Anthony Albanese told reporters: "We have a strong relationship between our two countries, but in Sir Keir Starmer and Angela Rayner and so many others who I am very familiar with in the British Labour Party, I look forward very much to working with them.

"They have very similar views to us on a range of issues. I'm sure we'll work closely on AUKUS, where we worked very closely as well with the former government."

Canadian Prime Minister Justin Trudeau said on X: "Congratulations, @Keir_Starmer, on a historic U.K. election victory. Lots of work ahead to build a more progressive, fair future for people on both sides of the Atlantic. Let's get to it, my friend."

New Zealand Prime Minister Christopher Luxon said on X: "Congratulations @Keir_Starmer on your election victory. New Zealand and the UK are great friends and can do so much more together. I look forward to working on every opportunity together as prime ministers. Thank you @RishiSunak for your service to your nation and friendship to New Zealand."

The UK's Labour Party swept to power early on Friday after winning the country's general election, crossing the 326-seat threshold for a working majority in the House of Commons.

"A mandate like this comes with a great responsibility," Labour leader Keir Starmer told supporters at a triumphant dawn rally in London, moments after the results that sealed its landslide win were announced.