Zaha Hadid has accused Japanese authorities and architects of colluding over the Tokyo 2020 Olympic stadium project, and says that Kengo Kuma's replacement design has "remarkable similarities" to her own.

The London-based architect, who was ousted from the job in July two years after winning a competition to design the stadium, said that she had been treated shockingly.

"Sadly the Japanese authorities, with the support of some of those from our own profession in Japan, have colluded to close the doors on the project to the world," she said.

The Japan Sport Council (JSC) announced earlier today that Kengo Kuma's design will be built in Yoyogi Park to host the opening and closing ceremonies for the 2020 games, as well as athletics, football and rugby events.

Hadid claims the replacement design has a similar shape and layout to her proposal, which was attacked by numerous Japanese architects including Kuma for being too big and too expensive.

"This shocking treatment of an international design and engineering team, as well as the respected Japanese design companies with whom we worked, was not about design or budget," she said.

"In fact much of our two years of detailed design work and the cost savings we recommended have been validated by the remarkable similarities of our original detailed stadium layout and our seating bowl configuration with those of the design announced today."

Work is expected to start on the stadium in 2017 and complete by November 2019. But Hadid says construction could have started already if her scheme hadn't been scrapped.

"Work would already be underway building the stadium if the original design team had simply been able to develop this original design, avoiding the increased costs of an 18-month delay and risk that it may not be ready in time for the 2020 Games," she said.

Hadid won the original competition to design the stadium back in November 2012.

It came under fire from a host of Japanese architects including Toyo Ito, Sou Fujimoto and Riken Yamamoto for its scale, but was eventually scrapped because of spiralling costs.

Hadid says this rise was due to a 25 per cent rise in costs across Tokyo's construction market, and claims the authorities used costs as an excuse to swap her for a Japanese architect.

"They don't want a foreigner to build in Tokyo for a national stadium," Hadid told Dezeen at the time.

Costs for the stadium began at ¥130 billion (£707.1 million) but rose to ¥252 billion (£1.37 billion) in 2015. Kuma's design team will have to work to a revised budget of ¥155 billion (£843 million).

Portrait of Zaha Hadid by Mary McCartney.