LONDON, June 26 (Reuters) – Britain’s opposition Labour leader Jeremy Corbyn sacked his foreign policy chief on Sunday, a spokesman said, plunging the party into open conflict after Britain voted to leave the European Union. 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. A growing number of Labour lawmakers have called on Corbyn to resign in the aftermath of the vote to leave the EU. 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