Sky News understands that Robert Sinclair will leave the privately owned airport in Docklands in January after six years in the role.

An announcement about his move to HS1, which is also backed by private investors, is expected later on Friday morning.

Mr Sinclair's exit will come several months after London City Airport suffered a setback to its expansion plans, with Newham Council rejecting an attempt to boost its annual passenger numbers from six-and-a-half million to nine million.

The airport is appealing against the decision.

The airport is owned by a consortium of Canadian pension funds and Kuwait's sovereign wealth fund.

It is also expected to announce on Friday that Rob Holden, its chairman, will step down after steering it through the challenges of the post-Brexit period and the pandemic.

He will be replaced by Mel Ewell, a board member since 2017.

A search for Mr Sinclair's successor will kick off immediately, with finance chief Wilma Allen and chief operating officer Alison FitzGerald running City Airport after his exit on an interim basis.

At HS1, he will replace Dyan Perry, who is retiring at the end of the year after seven years in charge of the rail link between St Pancras International and the Channel Tunnel.

"It has been an immense honour and privilege to lead London City Airport over the last six years during an incredibly exciting and challenging period," Mr Sinclair said.

"London City is regularly voted as London's favourite airport, and this is testament to the hard work, commitment and friendly service provided by everyone who works here."