The demolition of the Kagawa Prefectural Gymnasium in Japan by Pritzker Architecture Prize-winning architect Kenzo Tange has been announced, sparking a petition to save it.

Completed by Tange in Takamatsu in 1964, the post-war landmark has been under threat of demolition since 2014 when it was closed due to a roof leak.

It has now been confirmed by local governor Toyohito Ikeda that the iconic boat-like structure, which is in need of an extensive retrofit, will be torn down.

The news sparked criticism from the local architecture community, which launched a petition campaigning for its preservation. At the time of writing, it has almost 4,000 signatures.

Among the campaigners is local architect Noriyuki Kawanishi, who had visited the gymnasium since childhood and told Dezeen that the news has made many people "very sad and angry".

"I feel very sad when I imagine the loss of this building that was a part of my daily life," Kawanishi told Dezeen.

"There are many people in the prefecture who have had similar experiences to mine, and it is their support that has allowed us to continue our activities."

Decision made without public consultation

The concrete Kagawa Prefectural Gymnasium was designed by the late architect Tange in the 1950s. It has a distinctive oval structure rising at both sides and supported by four giant pillars. Its form was intended to echo a traditional Japanese wooden boat.

In 2014, the building was closed after the rusting of the suspension cables supporting its concrete roof caused a leak. Its unusual design has made this difficult to repair.

According to Kawanishi, the decision to demolish the building was decided by the prefectural government without public consultation.

"I believe that some politicians within the prefectural government who do not understand culture and the arts are strongly pushing for its dismantling," said Kawanishi.

"However, the political movement is not open to the general public, and the decision to dismantle the gymnasium was made without even open discussion."

Though the timing of its dismantling is yet to be disclosed, Kawanishi believes work could begin as soon as two years from now. The architect also suggested there had been a lack of effort to raise the funds for the preservation – which would cost two billion Japanese yen (approximately £12 million).

"The cost of the seismic retrofitting of the Kenzo Tange-designed gymnasium is said to be two billion Japanese yen, an amount that cannot be borne by an individual or local company," Kawanishi said.

"The Japanese government and well-known companies are needed to overcome the current situation, but Kagawa Prefecture has not taken any such action since the closing of the gymnasium."

Demolition threatens Japan's architectural heritage

Kawanishi is also calling for greater public awareness of the importance of architectural preservation in Japan.

The news of the demolition of Kagawa Prefectural Gymnasium follows the recent destruction of Nakagin Capsule Tower, an iconic housing block in Tokyo. Designed by architect Kisho Kurokawa in the metabolism style, the tower was composed of a series of modular capsule homes.

Kawanishi believes that the demolition of these iconic buildings will lead Japanese cities to "lose their appeal".

"[There is often] a strong belief that it is good to tear down the old and make way for the new," Kawanishi explained.

"I believe that if Japanese people do not have a better idea that buildings create cityscapes and their appearance indicates the richness of life, the Japanese cities of the future will become more uniform and lose their appeal."

SANAA constructed sports facility nearby

The future of the Kagawa Prefectural Gymnasium site is yet to be determined with a new sports facility designed by SANAA currently being built nearby in Takamatsu. The World Monuments Fund has previously warned this new venue could be a threat to the future of the gymnasium.

For this reason, the World Monuments Fund included the building in its 2018 World Monuments Watch – making it one of eight endangered heritage sites that shared $1 million (£831,440) for preservation efforts.

Kagawa Prefectural Gymnasium is the latest of many ageing heritage buildings that are at threat of demolition around the world today.

Other significant buildings that could soon face the wrecking ball are the dormitories at the Indian Institute of Management Ahmedabad in India by American architect Louis Kahn after the school backtracked on its decision to save them.

Elsewhere, the derelict Miami Marine Stadium in Florida by Cuban-American architect Hilario Candela was recently identified as one of the most under-threat modern buildings in America.

The main photo is by Noriyuki Kawanishi.