"While I will not be participating, I wish the contingent the best at Asian Games and to do Singapore proud," the 28-year-old swimmer, who won the 100 metres butterfly title at the Rio 2016 Olympics,  said in a statement.

"The status of my training and competition remains the same.

"More details of my future will be shared in due course."

The Team Singapore contingent has been chosen across 32 sports.

At the official flag presentation ceremony held at OCBC Square fencer Amita Marie Nicolette Berthier and wushu athlete Jowen Lim were unveiled as the flagbearers for the Asian Games, with the former doubling up as the pledge taker.

At the ceremony, Singtel announced the renewal of its partnership with the Singapore National Olympic Council with the sponsorship of S$1.7 million (£1 million/$1.27 million/€1.17 million) in cash and kind support of Team Singapore athletes over the next five years.

Guests-of-honour Alvin Tan, Minister of State, Ministry of Culture, Community and Youth and Ministry of Trade and Industry, and Jessie Phua, Acting President of SNOC presented the Singapore flag to the Chef de Mission, Dr Koh Koon Teck, who then handed the flag over to the flagbearers.

Teck said: "We are sending our largest Team Singapore contingent to the Asian Games.

"The athletes have their targets set and will be working closely with their performance team to meet them.

"I am confident that if they continue to train well and keep their focus, they will be able to perform to the best of their ability in Hangzhou.

"This year we have also seen impressive performances from our athletes at the Cambodia 2023 Southeast Asian Games as well as at other competitions, and I hope Singaporeans can join us in encouraging them to continue to put their best form forward for Singapore."

Schooling pulled out of the Southeast Asian Games held in May, saying he was "not at the level" to do his best.

Singapore Aquatics told The Straits Times newspaper that two swimmers had clocked faster times than Schooling during the qualification window for Hangzhou 2022.

Schooling, who has been performing two years of mandatory military service, was mired in a drug controversy last year, AFP reports.

He tested negative, but confessed to consuming cannabis overseas.

Singapore has some of the toughest drug laws in the world, and its citizens and permanent residents face up to 10 years in prison if found to have consumed illegal substances outside the city-state.

Schooling was given a warning and placed on a supervised urine test regime for six months.

He was also made no longer eligible for leave or disruption to train or compete during his military service.

Schooling caused a sensation at Rio 2016 when he beat Michael Phelps to win the 100 metres butterfly.

He failed to qualify for the same event at Tokyo 2020, however, and has dropped several hints that his career is coming to an end.

The 2022 Asian Games - postponed by a year because of China’s strict zero-COVID rules - will be held in Hangzhou from September 23 to October 8.