Dhaka - The Japanese head coach of Bangladesh's national swimming federation has quit after alleging that junior swimmers were forced to do punishment exercises in the blazing sun for using their phones too much.

Announcing his resignation on Facebook, Takeo Inoke, who was hired in August ahead of the South Asian Games in December, said he had "zero tolerance" for physical punishment.

Inoki said that a group of juniors were given "meaningless physical exercise" in temperatures of 40 degrees Celsius (104 Fahrenheit) on Sunday for breaching rules limiting their mobile phone usage.

Forced to wear long sleeves and tracksuit bottoms in the hot sun, the children had to run, do somersaults and frog jumps on a hard tiled floor. One of them then collapsed to the ground.

The girl was left lying for about 10 minutes and when Inoki raised his concerns, the other coaches "were laughing and saying that she was acting and we should leave her there."

Eventually she was brought to a shaded area but Inoki said he was told there was no ice and no phone to call an ambulance. Finally she was taken away "to somewhere" by van, he said.

Inoki said he would notify FINA, the world swimming federation, and that he hoped this "sad incident would became (a) critical tuning point into building a new competitive swimming organization and structure in Bangladesh."

Bangladesh Swimming Federation chief M.B. Saif said they were "surprised" at the resignation.

"The swimmers are allowed to keep a phone with them only one day a week. They broke the rule and were punished. Usually these punishments are not very harsh," he said, adding a probe has been ordered.

Physical punishment of children and teenagers is widespread in Bangladesh although corporal punishment has technically been banned since 1995.

A study by UNICEF in 2009 year found that nine out of 10 children in Bangladesh are physically beaten in school, with seven out of 10 reporting they receive similar treatment at home.

In Japan, sports clubs have been plagued by accusations of tolerating the harassment and physical punishment of players and brutal hazing rituals.