Singapore requires all male citizens aged 18 to serve two years in the military, the police or emergency services.

Schooling was originally supposed to attend national service in 2014, but had it deferred to train for the 2016 Olympics in Rio de Janeiro.

He claimed gold in the men’s 100 metres butterfly at the Games, overcoming his idol Michael Phelps, the American who has won 23 Olympic gold medals and is the most-decorated Olympian of all time.

Schooling was given another deferment to train for Tokyo 2020, but the Games were moved to July and August 2021 due to the ongoing COVID-19 pandemic.

Schooling and Quah both applied for an extension, which has now been granted by the Singapore Ministry of Defence (MINDEF).

The applications were backed by the Armed Forces Council and the Ministry of Culture, Community and Youth (MCCY).

"The deferments are for Mr Schooling and Mr Quah to train for and compete in the Olympic Games that have been postponed to 2021,” a MINDEF statement read.

"Both have qualified for the coming Olympic Games - Mr Schooling for the 100-metre butterfly event, and Mr Quah for the 100-metre butterfly and backstroke events.

"Should the Olympic Games be cancelled, they will be scheduled for enlistment.

"Deferment may be granted to exceptional sportsmen who are assessed to be potential medal winners for Singapore at top-tier international competitions like the Olympic Games.

"Applicants will have to show why deferment is necessary for them to compete successfully at these competitions and bring national pride to Singapore.

"Mr Schooling and Mr Quah have met the criteria for deferment to be extended.

"They have also committed to be fully focused in their preparations for the Olympic Games, in order to reach their peak form and will not undertake any additional activities such as commercial sponsorships.

"MINDEF extends its best wishes to Mr Schooling and Mr Quah as they pursue national pride for Singapore in the Olympic Games in 2021.”

Schooling’s gold medal at Rio 2016 was Singapore’s first at an Olympic Games.

The 25-year-old has also secured two World Championship bronze medals during his career, as well as three gold medals at the Asian Games.

Schooling has won 27 gold medals at the Southeast Asian Games, the fourth highest total achieved by an athlete in the history of the event.

He is the most successful male athlete at the Games.

Quah has claimed 23 gold medals at the Southeast Asian Games during his career.

The 23-year-old is looking to compete at a third Olympic Games, having represented Singapore as a teenager at both London 2012 and Rio 2016.