The memo, which follows British media reports that Vinals has been sounding out replacements for Winters, did not mention any timeline, but the bank's strategic plan is set to run until at least 2021.

A spokeswoman for the bank confirmed the contents of the memo.

"I want to comment on recent press speculation about CEO succession at major UK banks, including at Standard Chartered," Vinals said in the memo sent to all staff.

"Both Bill and I have said unequivocally that (we) intend to work together through the delivery of our strategy and the transformation of our bank," he said.

Vinals' backing of Winters will be seen as a strong signal of support by staff at the bank, after the Chief Executive has drawn criticism over the last two years from investors disappointed by the lender's performance.

Former JPMorgan banker Winters won plaudits from investors during his first three years at the lender from 2015 to 2018 when he repaired its balance sheet and overhauled its lending culture.

He has since endured a tougher time. The bank's share price has languished as it struggles to grow revenues, and some investors criticized his pension allowance for being above that of the wider workforce.

StanChart's share price has nearly halved since Winters joined in 2015, as the bank suffered from slowing global trade, low interest rates and the costs of its own restructuring.

CHANGES AT THE TOP

Vinals alluded in the memo to a spate of changes at the top of some of Europe's biggest banks.

HSBC is hunting for a chief executive to replace John Flint, ousted last August and replaced by interim boss Noel Quinn, who is jockeying for the full-time role.

Quinn did not get the job as some expected at the bank's annual results presentation, however, and media reports said Chairman Mark Tucker preferred UniCredit Chief Executive Jean Pierre Mustier or another external candidate.

Mustier subsequently ruled himself out of the HSBC job.

Meanwhile Credit Suisse boss Tidjane Thiam left last month following a spying scandal, and Swiss rival UBS is replacing Sergio Ermotti with ING's Ralph Hamers.

Barclays CEO Jes Staley is also under pressure from an activist investor who wants him to cut back its trading business, and regulators probing his past ties to the deceased U.S. financier Jeffrey Epstein, who killed himself awaiting sex trafficking charges.

Staley has said he did not know Epstein's true nature and that he regrets the relationship.

By Lawrence White