Mayor of London Boris Johnson has pledged that taxpayers won't foot the bill for the upkeep of the Garden Bridge.
The Mayor was questioned about the maintenance costs by anti-Garden Bridge campaigner Wai-King Cheung during his monthly 'Ask Boris' phone-in on LBC this week.
"The maintenance costs will not be borne by the public sector," said Mr Johnson, who has funded the capital costs of the bridge through Transport for London to the tune of £30 million.
A further £30 million has been pledged by central Government, taking the public sector contribution to £60 million.
When Westminster councillors approved their half of the bridge last December they imposed a condition that the Garden Bridge Trust must provide a suitable surety or guarantee that future maintenance costs can be met before work on the river crossing can begin.
Westminster Council suggested that Transport for London might be a suitable body to provide that guarantee.
The Mayor added: "The bridge will be a wonderful thing ... because it will reanimate that whole Aldwych area which is a mess at the moment ... [and] it will drive footfall across to the South Bank."
He continued: "It will be a new park for London. It will be a new space where people can relax."
Opponents of the Garden Bridge have launched a crowdfunding campaign to raise funds for a legal challenge. So far £1,500 of the required £24,000 has been raised.
Donors include architecture critic Rowan Moore who has pledged £50 to the campaign. Last year he described the Garden Bridge as "an ill-informed gamble with one of the great places of Britain".