A hotelier who gave £5m towards revamping Edinburgh's West Princes Street Gardens has resigned from the project's board.
Apex Hotels founder Norman Springford said his motivations had been questioned and he had been accused of trying to privatise the park.
He said despite this being "completely untrue" it had "become a distraction to the project's ambitions".
The board will decide on a new chairperson at the end of this month.
Mr Springford was a figurehead for The Quaich Project, a public-private partnership between the Ross Development Trust and City of Edinburgh Council, which aims to transform the 19th Century gardens.
The plan is to create an open-air arena to replace the Ross Bandstand and redevelop the gardens as an accessible public space.
But there has been criticism after reports that firms were being invited to sponsor parts of the project. in return for corporate branding.
Mr Springford, the founder of The Ross Development Trust, said: "Since we started this project there has been an underlying perception that our intentions are either commercial or to privatise the gardens. This is of course completely untrue.
"In particular, my motivations have been questioned. I believe that this has become a distraction to the project's ambitions which are honourable and would ultimately benefit all of Edinburgh.
"It is for these reasons, that I have decided to take a step back to allow someone else to lead the project and to give it the best chance of being realised.
"The original vision, which continues to be held dear by the board and team, is purely to improve these loved but underfunded gardens."
David Ellis, managing director of The Quaich Project said: "Norman's vision and generosity is an example to everyone, and we are extremely grateful to him for taking the project so far. The heart of this project is creating something good of the people of Edinburgh and Norman has worked tirelessly to achieve that."
Donald Wilson, City of Edinburgh Council's culture and communities convener, said: "As well as being a passionate advocate for the future of West Princes Street Gardens, Norman Springford has led the Ross Development Trust through some of its most exciting recent developments including the upgrade of the Gardeners Cottage and restoration of the iconic Ross Fountain.
"I would like to thank Norman for his generous contribution and commitment to the project and we look forward to working with the new chair to make sure everyone can access and enjoy this wonderful asset for generations to come."