The skimpy trunks sported by Singapore's men's water polo team are causing red faces back home in the conservative city-state, with many embarrassed by their design.

The trunks display the Singaporean flag's white crescent moon on the front of the red briefs in what has been described as an inappropriate fashion.

The design - lambasted by readers of Singapore's Straits Times newspaper as "disgusting", "nauseating" and "disgraceful" among other terms - had not been approved by the country's Ministry of Information, Communication and the Arts (Mica), which governs the use of the flag.

"We would have told them that their design is inappropriate, as we want elements of the flag to be treated with dignity," Singapore media quoted a Mica marketing official as saying.

Few Internet users had given the trunks the thumbs up, many seeing them an insult to the Southeast Asian nation's dignity.

"There are 1000s of ways to show patriotism (sic) but sadly regrettably the chap who designed these trunks choose to do it in this disgusting and disrespecting way," one post read on the Straits Times website.

The trunks had also left the water polo team red-faced but ultimately powerless to do anything about it.

"The competition rules state that the trunks must be presented at that start of competition and they must be used throughout the tournament," Jose Raymond, the Singapore delegation's head of public relations, said.

"The team can't use other trunks."

Raymond said the team was "apologetic if they've offended anyone in any way... they meant the flag no disrespect."

Raymond also confirmed the trunks' design would be tweaked upon the team's return home, after local media quoted a Singapore swimming official saying the crescent moon was supposed to be placed "more towards the side."