Labour is seen as being “unfriendly to business”, according to the party's most senior elected politician, London mayor Sadiq Khan.
Khan said the City of London in particular had “unease” with Labour both in the 2015 general election and under its current leadership.
A spokesman for Labour leader Jeremy Corbyn declined to respond to Khan's comments
Sources close to Corbyn's challenger Owen Smith acknowledged a problem, but said only: “We will be talking about how business can play a part in a prosperous economy in the coming weeks.”
Speaking to the Sunday Telegraph, Khan added it was an embarrassment that his party appears “uncomfortable around success”, and declared himself an advocate for wealth creators.
“I accept the unease the City had with Labour in the 2015 General Election. And particularly with the current leadership the national party has got,” he said.
Khan added that he is continuing to lobby Brexit secretary David Davis over the access to passporting rights for UK institutions, allowing them to transact business on the continent.
“I want JP Morgan and others to know the mayor is on their side. I want them to stay here, they are welcome here,” he said.
Despite his comments, Khan refused to enter into direct comment on his party's leadership election, but added that Labour's best chance of defeating the Conservatives is to be pro-business.
“You can't win elections...just speaking to your core vote. My nervousness about the Labour leadership is, who are we talking to? We're just talking to ourselves.”