A teacher has been fired from his job at an Adelaide private school for suggesting to a student that he could be her "sugar daddy".

Key points: Adelaide teacher suggested to a student he could be her 'sugar daddy' in March

Adelaide teacher suggested to a student he could be her 'sugar daddy' in March He was dismissed by his Catholic school in May

He was dismissed by his Catholic school in May The Fair Work Commission upheld the school's decision

The Fair Work Commission threw out the former St Columba College middle school teacher's claim of unfair dismissal just before Christmas, after his position was terminated in May.

The commission's deputy president, Peter Anderson, found the 50-year-old teacher had acted inappropriately to a female Year 11 student at the school, including by suggesting that he could pay her an allowance, and that he would be better than her boyfriend was.

The alleged conduct happened at the school's sports carnival in March, when the teacher called her over to help rake sand during an event.

The commission heard he told the student — who he had previously taught — that her boyfriend was not nice enough for her.

"He said words to the effect, 'I can treat you better. I can be your sugar daddy. I can pay you small allowances. We can drink red wine. You can give me neck massages'," the student alleged in evidence to the commission.

The student said she was also made uncomfortable by the teacher standing near her as she bent over to rake the sand.

She told her mother and teachers about the incident the same day.

Teacher denied making remarks

The teacher emphatically denied making the statements, including the term "sugar daddy", and claimed to be "thinking out loud" about getting a massage.

He was also found to have unreasonably intruded on the 16-year-old's personal life by seeking her out at the northern suburbs supermarket she worked at.

The teacher had previously worked as a massage therapist. ( pixabay )

Mr Anderson found he would "often if not always" go to the checkout staffed by the student, even when other checkouts had shorter queues or he had very few items.

He said the behaviour "raises reasonable suspicion about his intent".

The commission heard that several day before the sports day incident, the teacher had visited the store twice in an effort to see the student.

He had asked her during the week what shift she was working, but this was changed by the employer at the last minute.

The teacher denied visiting the store twice in one day.

The commission noted that the student's workplace was around 12 kilometres from the teacher's home, and multiple other outlets were closer.

Teacher's evidence deemed 'evasive'

The teacher claimed his dismissal was harsh, unjust or unreasonable, and was seeking his position be reinstated.

He said his dismissal was harsh because it would impact on his future employment prospects.

Mr Anderson said he was "well satisfied that [the teacher] used the words 'sugar daddy'", describing his behaviour as "inappropriate, unprofessional and a valid reason for summary dismissal".

"The conduct was recklessly indifferent to the legitimate rights of the student," he wrote in his findings.

The teacher had previously received warnings about his conduct with students. ( ABC News. )

Mr Anderson said he treated the teacher's evidence with caution, finding it to be "conveniently selective" and "not persuasive".

"Overall, the character of this evidence was evasive; designed to avoid making a damaging admission but to appear reasonable by not denying all elements of the allegations except the most grave," he wrote.

He had previously been the subject of three formal disciplinary incidents during his employment at the school, including allegations of inappropriate physical and verbal contact toward students.

He disputed all three incidents, but Mr Anderson noted that by virtue of issues being raised "ought to have caused him to again reflect on the boundaries of appropriate conduct".

"That a teacher with experience and who had (whether rightly or wrongly in their view) been cautioned about past behaviours, would nonetheless undertake such conduct suggests a cavalier disregard of professional obligations."

Evidence from the Catholic Education Office suggested that the Teachers Registration Board had been made aware of his dismissal and the allegations, and was considering the teacher's registration.