Britains opposition Labour leader
The EU referendum, which saw 52 percent of Britons voting to leave the EU, has begun to transform Britain's political landscape, triggering leadership battles in both the ruling Conservative Party and opposition Labour.
Corbyn sacked foreign spokesman Hilary Benn overnight because "he has lost confidence in him", a spokesman said. His dismissal was followed on Sunday by the resignation of Labour's shadow health minister, Heidi Alexander, whose statement demanded a change in the party's leadership.
Some party members say he failed to assuage concern among the party's traditional supporters over the EU; others that he should have campaigned more in favour of EU membership.
Two Labour politicians have submitted a motion of no confidence in Corbyn, which will be debated later this week.
Corbyn's spokesman gave no details on Benn's dismissal, but Benn said he had told Corbyn there was widespread concern in the Labour Party about his leadership, after which Corbyn had dismissed him.
The Observer newspaper had reported that Benn, who publicly disagreed with Corbyn in September over air strikes on Syria, was gauging support for a move to oust Corbyn.
"In particular, there is no confidence in our ability to win the next election, which may come much sooner than expected if Jeremy continues as leader," Benn said in a statement.
As things stand, Britain is due to elect a new parliament in 2020. A new Conservative leader will automatically become Britain's new prime minister, but may seek to call an early election to obtain a personal mandate to govern.
Some Labour lawmakers called on the other members of the shadow cabinet - top policy chiefs who hold portfolios mirroring those of the government - to resign from their positions.
"Lots of good people chose to serve in Shadow Cabinet to keep the show on the road. There are no longer good reasons for good people to stay," Labour lawmaker Wes Streeting said on Twitter.
Colleague Ben Bradshaw called on the shadow cabinet to "act to save the party and for the sake of the country".
On Saturday, Corbyn rejected the calls for him to resign.
Asked whether he would stand for re-election in any leadership contest, he said: "Yes, I'm here."