London (AFP) - Rishi Sunak on Tuesday became Britain's third prime minister this year and the first person of colour to lead the former imperial power, vowing to overcome economic crisis provoked by the "mistakes" of Liz Truss's calamitous 49-day tenure.
Sunak addressed the nation outside 10 Downing Street shortly after his appointment by King Charles III, capping the latest extraordinary twist in UK politics following Boris Johnson's demise in July.
"Right now our country is facing a profound economic crisis," said the former finance minister, a practising Hindu who at 42 is Britain's youngest leader since 1812.
"I will unite our country -- not with words, but with action," Sunak said, also pledging unstinting support for Ukraine even while warning of "difficult" budget choices ahead.
Departing shortly before, Sunak's predecessor Truss wished him "every success" -- and said she remained "more convinced than ever" that Britain needed to be "bold" in confronting the challenges it faced.
Sunak countered that the disastrous budget that felled Truss was motivated by a well-intentioned desire to kick-start growth, but its tax-cutting measures were "mistakes nonetheless".
"And I have been elected as leader of my party and your prime minister in part to fix them," he said.
"And that work begins immediately.I will place economic stability and confidence at the heart of this government's agenda," he added, helping to drive the pound more than one percent higher against the dollar Tuesday.
Sunak became the ruling Conservatives' new leader on Monday after triumphing over rival contender Penny Mordaunt, who failed to secure enough nominations from Tory MPs.
'Groundbreaking'
It had become a two-way fight after Johnson dramatically aborted a comeback attempt late on Sunday.
Breaking his silence, Johnson offered his "full and wholehearted support" to Sunak -- having privately blamed his ex-minister for toppling him in July.
Sunak in turn praised Johnson, and vowed to build on the election-winning promises that earned the Conservatives a big victory in 2019, despite their dismal standing in polling today against the opposition Labour party.
But Sunak also issued a coded reminder of the many scandals that brought Johnson down, vowing his own premiership would offer "integrity, professionalism and accountability at every level".
US President Joe Biden called the appointment of the first British-Indian prime minister "groundbreaking" and "pretty outstanding".
"Together, I look forward to enhancing our cooperation on issues critical to global security and prosperity, including continuing our strong support for Ukraine," Biden said in a tweet.
European leaders offered their own congratulations, while Irish premier Micheal Martin reminded Sunak of their "shared responsibility" to safeguard peace in Northern Ireland following tensions under Johnson and Truss.
Labour leader Keir Starmer praised Sunak on "making history as the first British-Asian PM".
But he added: "The Tories have crashed the economy, with low wages, high prices and a cost-of-living crisis.The public needs a fresh start and a say on Britain's future."
Sunak has rebuffed opposition calls for a snap general election after becoming the latest leader who lacks a direct mandate from the electorate, but he promised to govern on the basis of the 2019 manifesto.
Pollster Ipsos said on Monday that 62 percent of British voters do want an election by the end of the year.
'Unite or die'
Britain's Conservative-supporting media hailed the appointment of Sunak, a wealthy descendant of immigrants from India and East Africa.
"The force is with you, Rishi," ran The Sun's headline, playing on his love of "Star Wars" films.
But the left-leaning Guardian highlighted Sunak's warning to Conservative MPs that the party must "unite or die".
Truss left office as the UK's shortest-serving premier in history, after her disastrous tax-slashing budget sparked economic and political turmoil.
The 47-year-old announced her resignation last Thursday, admitting she could not deliver her mandate from Conservative members -- who had chosen her over Sunak in the summer to replace Johnson.
Iain Duncan Smith, a former Conservative leader, said MPs now understood the "existential threat" facing the Tories, and that they needed to unite or accept being "out of power for a long time".
Sunak started appointing his top team, before facing his first session of "Prime Minister's Questions" in parliament on Wednesday.
Finance minister Jeremy Hunt -- appointed by Truss just 11 days ago in a futile bid to salvage her premiership -- could remain in the role after stabilising the markets.
