Radical left-winger Jeremy Corbyn has won the crown of Britain's main opposition Labour Party in a landslide victory, becoming the nation's most left-wing political leader for more than 30 years.
The 66-year-old socialist, whose policies have been compared to those of Greece's Syriza and Spain's Podemos, was named leader after clinching 59.5 percent of the 422,664 votes cast by Labour Party members and supporters.
The newly elected leader condemned "grotesque levels of inequality" and "an unfair welfare system" in his victory speech to party members in central London.
The veteran campaigner also called for Britain's Conservative government to show more "compassion" in dealing with the Syrian refugee crisis and said he would attend a demonstration planned in London later on Saturday.
He said Labour was "united and absolutely determined in our quest for a decent and better society that is possible for all".
North Islington MP Corbyn has electrified Labour's leadership race, which was triggered by the resignation of Ed Miliband after he lost May's general election to David Cameron's right-wing pro-austerity Conservatives.
"The fight back now of our party gathers speed and gathers pace," Corbyn said in his speech.
The veteran MP comfortably beat the three other more centrist candidates in the race - Yvette Cooper, Andy Burnham and Liz Kendall - who all had far stronger support from fellow Labour MPs.
"Jez we did!" his delighted supporters chanted in the conference room in reaction to the decisive outcome.
Corbyn has spent 32 years on Labour's backbenches and only won a handful of votes from his own MPs - but was swept to victory on a wave of enthusiasm from Labour supporters following the end of the Miliband era.
The stunning result has however sparked talk of a deep split within Labour, which was thrown into turmoil by Cameron's shock election win in May.
Corbyn's policies include spending more on public services like schools and hospitals, scrapping nuclear weapons, renationalising industries like the railways and involving Islamist groups Hamas and Hezbollah in Middle East peace talks.
In a positive omen for Corbyn, Sadiq Khan - who nominated the veteran left-winger for the Labour leadership - was elected as the party's 2016 London mayoral candidate on Friday.
Khan, who did not actually vote for Corbyn, comfortably beat Blairite former Olympics minister Tessa Jowell, boosting media speculation over a landslide for the Islington North MP.
UK press divided on new Labour leader
Britain's pro-Conservative Sunday newspapers have crowed that socialist Jeremy Corbyn's crushing leadership victory would condemn the Labour Party to the opposition for a long time, while leftist media hailed the win.
'Bye Bye Labour!' screamed a front-page headline in the Sunday Express and the Mail on Sunday published a picture of the new anti-austerity firebrand next to the words 'Red and Buried'.
'Death of New Labour,' said the Sunday Telegraph, referring to controversial former prime minister Tony Blair's famous brand from the 1990s.
'Labour isn't dead, Blairism is. Jeremy Corbyn finally killed it,' the paper said in an editorial that said "boring Blairites" had been vanquished.
The Sunday Times also picked up on the splits in the party and several figures who have said they will not serve under his leadership, with the headline: 'Corbyn sparks Labour civil war'.
Corbyn won with a landslide 59.5 percent announced on Saturday, far ahead of his three more centrist rivals Andy Burnham (19 percent), Yvette Cooper (17 percent) and Liz Kendall (4.5 percent).
The Independent on Sunday referred to Corbyn's appeal in his victory speech to new young Labour supporters and returning former members, with a headline saying: 'Welcome to the party, welcome home'.
Guardian columnist Rafael Behr called Corbyn's election an earthquake "off the political Richter scale", pointing to the role of young people not previously involved in politics.
"Blairism is buried beneath the rubble and a different structural and cultural divide has been revealed," he wrote for the pro-Labour daily.
"It is between established Labour... and insurgent Labour, a complex hybrid of organised coup by dogged old warriors of the left and spontaneous, organic uprising by idealistic new recruits."
A special victory edition of the socialist Morning Star newspaper cheered his triumph.
'Jeremy Storms to Victory', said the paper, stressing that Corbyn had won with 59.5 percent of the vote compared to Blair's own leadership election with 57 percent in 1994.
Blair went on to win three successive general elections for Labour but is unpopular among leftwingers in the party because he led Britain into war in Iraq