Khan said that “the continuation of the project will expose the London taxpayer to additional financial risk, both with regard to the bridge’s construction and its operation and maintenance.”

The scheme has been on life-support for some time and the latest move looks to kill-off any chances of it being built.

Khan said: “Under the previous Mayor, a considerable amount of London taxpayers’ money has already been spent on the Garden Bridge.

“I have always been clear that not a penny more of taxpayers’ money should be allocated to the project.”Having assessed all the information available to me including the findings of Dame Margaret Hodge’s independent review, my view is that providing Mayoral guarantees will expose the London taxpayer to too much additional financial risk.

“With planning permission due to expire this year, many outstanding issues remain, including spiralling construction costs and doubts around funding the maintenance of the bridge.

“The funding gap is now at over £70m and it appears unlikely that the Trust will succeed in raising the private funds required for the project.

“I am simply not prepared to risk a situation where the taxpayer has to step in and contribute significant additional amounts to ensure the project is completed.”