Plans for a Holocaust museum next to the Houses of Parliament are in a "huge mess" and the whole project should be aborted, campaigners have told talkRADIO.
Revised proposals for the learning centre in Victoria Tower Gardens have been submitted for the memorial, which a government spokesperson said will "honour and remember" the victims and survivors of the Holocaust.
Excavations were set to begin today on the banks of the River Thames, and a government letter to Westminster City Council on 25 April seen by talkRADIO explains this would "allow tree officers to monitor the condition of the tree roots for the first time".
However, the project, which began in 2015 has been criticised by UNESCO, Historic England, The Royal Parks and campaign group, Save Victoria Tower Gardens.
Barbara Weiss from the Save Victoria Tower Gardens said: "We're talking about £50m of taxpayers money. They've designed it, they've changed it and now they're changing it again."
Ms Weiss, an architect and daughter of a Jewish refugee, said: "This is completely the wrong way around. They should be digging, finding out if they can build and then designing accordingly. These are wonderful 100-year-old plane trees."
The letter to the council reveals new plans include a smaller underground area and revised designs for the entrance pavilion, courtyard and surrounding landscaping.
Save Victoria Tower Gardens argue this will not achieve the centre's original purpose and a better location would be the Imperial War Museum one mile away.
"It's in a huge mess. They seem to be going from one nightmare to another", Ms Weiss added.
The Ministry of Housing, Communities and Local Government is overseeing the project, which is run by the Holocaust Memorial Foundation.
A spokesperson added: "The proposals have been developed with great sensitivity to the existing context and character of Victoria Gardens."