Leading Japanese architect Arata Isozaki says the stadium at the heart of plans for the Tokyo 2020 Olympics will look like a turtle.
The stadium at the heart of plans for the Tokyo 2020 Olympic Games will be dull and look like a turtle, a leading Japanese architect said on Thursday, adding to the row over the controversial venue.
The centrepiece for the Games, which was designed by British-Iraqi architect Zaha Hadid, has been scaled down by a local team since first being conceived, amid complaints over its hefty price tag and claims it would be an eyesore in one of the city's few green areas.
But the new venue, to be built on the site of the old national stadium, no longer has the verve of its original conception, said Arata Isozaki, the 83-year-old architect of the Palau Sant Jordi used in the 1992 Barcelona Olympics.
"Two years ago, I felt that the Zaha Hadid proposal ... was a design that presented an excellent image of a 21st century urban architecture," he said in an email to AFP.
"However, when I saw the revised proposal ... I was shocked to see that the dynamism presented in the original had gone," he said.
"What remains is a dull, slow form, like a turtle waiting for Japan to sink so that it can swim away," said Isozaki, who also designed the Palasport Olimpico for the 2006 Turin Winter Olympics.
The comments came after Japanese sports officials said they would scale back the building's size, bowing to growing criticism that it was too big and costly.
The national government says the showpiece venue, re-envisaged by a team of Japanese architects, will cost about $US1.6 billion ($A1.73 billion), down from the previous estimate of $US3 billion ($A3.25 billion).
But critics - a coalition of prominent architects and civil society groups - have scoffed at the price cut and say it will likely end up going way over budget anyway.
"The reason that the new national stadium proposal is straying off course is because of the insistence on selecting the proposal" instead of selecting the architect, Isozaki said.
Zaha Hadid's "professional skills are outstanding. No matter how difficult the situation ... she is capable of leaving her signature on the design," Isozaki said.
"It is not too late. Return to the winning decision. Commission Zaha Hadid to re-design the new national stadium under these new conditions," he said.
Tokyo governor Yoichi Masuzoe recently said the city would review the cost and environmental impact of plans to build 10 new sports facilities and renovate two existing buildings.