A high school basketball player at the centre of a scandal over his age claims he does not know how old he is because his mother does not remember when he was born.

Jonathan Nicola, who claimed to be South Sudanese, will remain in detention in Canada until a hearing on May 24 after he was deemed a flight risk by authorities, who believe he deliberately sought to deceive so he could accept a scholarship to Catholic Central high school in Ontario.

Nicola was arrested by border officials on April 15 after an anomaly appeared in paperwork submitted by his school to help him enter to the US to play basketball.

US authorities alerted their Canadian counterparts that Nicola's fingerprints matched those on a previous visa application by a man seeking to enter the US from Syria. In the previous application, the man's birth year was given as 1986, which would make him 29, not 17 as he claimed.

The 206cm basketballer, who is believed to have been born in Saudi Arabia, appeared at hearing on Tuesday (local time) where he did not speak. However, testimony from an earlier hearing was made public.

In it, Nicola claimed his mother did not know his age.

"I always keep asking what is the specific age that I was born, and she has told me that she could not remember," he said.

"Over [in South Sudan], not every year we study. We always keep moving to different schools, and over there, they do not ask your age. They do not ask you nothing."

Nicola said he was a religious person and not a liar.

"I pray to God," he said.

"If something bad happen to me here, I do not know what would happen to my mother back home because she is really sick. She has diabetes.

"I did not come here to harm any people or do something bad. All my goal is to study and get the education, so I can go back home, I can help my mother, I can help all my rest of the family."

Nicola asked to be let free so he could return home, but that request was denied.

"I understand your desire to [go home], but the way you have gone about doing that is frankly, quite illegal," Nicola was told by a Canadian border services adjudicator.