Controversial £50m plans to build a Holocaust memorial and learning centre in a London park will be published this autumn, the BBC has learned.
Critics of the project, to be built in Victoria Tower Gardens, say people who rely on the green space will lose out.
Royal Parks charity chair Loyd Grossman said there may be better locations, but he would wait to see the final plans before taking a formal view.
Ex-shadow chancellor Ed Balls said the UK would be proud of the memorial.
The scheme is expected to be completed by 2021.
Sir Eric Pickles and Mr Balls - the co-chairs of the cross party memorial advisory committee - insists that Victoria Tower Gardens - the royal park next to the Houses of Parliament - is the right location for the memorial.
Ex-Labour shadow cabinet member Mr Balls, who co-chairs the advisory committee, told the BBC: "I think there is an overwhelming desire in our society to have a proper memorial.
"What better place than close to Parliament? They have important memorials in Washington and in Berlin but we should have one in London."
Sir Eric, the Conservative co-chair and former communities and local government secretary, said: "All over Europe, new memorials are going up - in Romania, in Ukraine and we are seeing a brand new one in Austria.
"I think it's right. This is likely to be one of the most frequently visited Holocaust memorials anywhere in the world."
An estimated two million people use Victoria Tower Gardens every year.
The six-acre park already hosts a number of memorials including a statue of suffragette Emmeline Pankhurst and the Buxton Memorial to the abolition of slavery.
Last October, architects Sir David Adjaye and Ron Arad won the competition to design the memorial and subterranean learning centre.
Speaking to the BBC, Loyd Grossman questioned the planned site of the memorial.
"There are many alternative locations which may very well be better in terms of protecting the natural environment; in terms of crowd management; in terms of security and indeed even in terms of existing expertise," he said.
However, he made it clear that the Royal Parks charity could not take any view of the current proposals until they were formally submitted to Westminster Council this autumn.
"We can neither object to it nor support it because we don't know what it is and we won't know what it is until a planning application is submitted," he said.
"However what's pretty obvious is the point of our charity. Our mission is to preserve historic open spaces for the public benefit. The public realm is under attack everywhere and we are protecting the public realm."
Barbara Weiss, a local architect who refurbished the Wiener Library - a Holocaust archive in London, is campaigning against the proposed location of Victoria Tower Gardens.
"There is something about the scale of this enterprise," she said.
"The park is a real oasis and it doesn't deserve to be taken over by something which is very bling and bombastic."
Ms Weiss also said the proposed excavation work posed a significant threat to the root system of the large plane trees in the park.
"We have commissioned experts who say the trees will be dead within 10 years."
Other organisations including the London Parks and Gardens Trust also oppose the decision to site the memorial in the park.
The Imperial War Museum, less than a mile from Victoria Tower Gardens, also believes the proposals for the learning centre could detract from its own plans to open a new digitally enabled learning and events suite to complement its current Holocaust exhibition.
It has been the national museum for the Holocaust since 2000.
But Mr Balls believed the planning process would deal with any concerns raised.
"We've chosen a design which means that the park is maintained as a public green space within which there is a beautiful memorial," he said.
"I think though that Britain will be not only very proud of this memorial but also very proud that we as a democracy have chosen to put a memorial to the greatest tragedy of the 20th Century next to our Parliament"
The memorial and learning centre design can be viewed here.