Bernie Sanders in full swing. Thomson Reuters LONDON — American left-wing firebrand Bernie Sanders has congratulated Labour leader Jeremy Corbyn on a successful UK general election campaign.

Sanders, who lost out to Hilary Clinton in the battle to become the Democratic presidential candidate last year, said he was "delighted" for Corbyn. He added that the vote sent an important socialist message.

"All over the world people are rising up against austerity and massive levels of income and wealth inequality," he told Washington Post reporter Dave Weigel.

"People in the UK, the US and elsewhere want governments that represent all the people, not just the 1%. I congratulate Jeremy Corbyn for running a very positive and effective campaign."

Corbyn is on course to secure 261 seats, up from 232 in 2015, a result that few expected when Prime Minister Theresa May called an election in April. May, who was predicted to win by a landslide majority, is expected to secure 319 seats, not enough for a Parliamentary majority. This is down on 331 on 2015.

It is not the first time Sanders has praised Corbyn. The Independent reported that Sanders offered his support to the Labour leader during a Cambridge Union speech. "Corbyn has shown a lot of courage in dealing with some of the economic issues," he said.