Corbyn said anti-Semitism was "absolutely abhorrent" and insisted his team had launched internal changes to tackle the problem from 2018.
Piers Corbyn confirmed on social media that he had been arrested and fined for his part in an anti-lockdown 'Unite for Freedom' protest at Trafalgar Square here on Saturday.
"Congratulations to @Keir_Starmer, the new Leader of the Labour Party!" UK's main opposition party announced on Twitter after a three-month leadership campaign.
Corbyn was elected Labour leader in 2015 in a shock result, after a political career spent on the sidelines of a party where few MPs share his staunch socialist views.
The vote will determine who gets to negotiate Britain's departure from the EU over the next two years.
Labour party leader Jeremy Corbyn has gained momentum during the election campaign and regularly attracts big crowds to his rallies.