Transport minister Andrew Jones told the House of Commons on Wednesday night that building the "iconic" Garden Bridge "will show that London is open for business".
Andrew Jones – parliamentary under-secretary at the Department for Transport – was responding to an adjournment debate secured by Vauxhall MP Kate Hoey.
Ms Hoey used the debate to warn that the proposed Garden Bridge between Temple and the South Bank risked becoming a "colossal white elephant" and that the £185 million project had been pushed through by a "cosy little cartel".
The Vauxhall MP said that she had initially found the idea of the Garden Bridge compelling.
"Once I had really looked into the Garden Bridge proposals, I realised that even if the concept seemed nice, it was in the wrong place," she told the Commons.
"There were other parts of the river where a transport crossing was far more needed. More crucially, there is the cost. This is not simply a local issue or even a London issue. It carries national significance in respect of the use of public funds and the delivery of a major infrastructure project in a specific location to the value of £185 million.
"In my view the arguments are very, very weak in respect of its need, supporting business case and, especially, location. Other areas of London have a significant need for investment of this sort, as do so many other important regions of our country."
The bridge is receiving £30 million from the Department for Transport and a further £30 million of public money from Transport for London.
In a wide-ranging speech Ms Hoey reserved particular criticism for her Labour colleagues on Lambeth Council.
She said: "The almost zealous support that has been given to the Garden Bridge Trust by Lambeth Council is disturbing.
"The chief executive has attended meetings with the Mayor's head of staff, David Bellamy, and the trust.
"The council's leadership has never allowed a proper, full debate in the council and a vote, and has ignored local councillors' views.
"Council officers and members have proceeded for three years without any policy basis. Their transport plan does not even mention the Garden Bridge, and there has been no policy paper from Lambeth explaining why the council should support it."
Responding to the debate, Andrew Jones explained that the Government had recently agreed to a request from the Garden Bridge Trust to be able to use some of the DfT's £30 million contribution to underwrite the costs of cancelling the project, should construction of the bridge not go ahead.
"To be precise, the Government will now underwrite £9 million of the cancellation costs, should they arise, with the private sector required to underwrite any such costs above that level," said the minister.
"The Government therefore continue to support the project and wish it well, but we have made it clear to the trust that not only public money should be at risk should the project fail.
"The challenge now for the trust is to focus its efforts on getting private sector backers to take on some of the risk. We have also reiterated that the Government have no intention of putting more than the £30 million originally pledged into the project – that is a cap."
The minister concluded by saying: "I hope we will have a project to show that London is a thriving, creative, bustling, ambitious city with all the talent in the world.
"It will show that London is open for business, and the Government wish it every success."
During the debate it was revealed that the minister responsible for the Government's support of the Garden Bridge project – Lord Ahmad of Wimbledon – has recently agreed to meet with Bishop's ward councillors to discuss local concerns.
• Mayor of London Sadiq Khan will be quizzed about his support for the Garden Bridge by Labour London Assembly member Len Duvall at Mayor's Question Time next Wednesday.