She was not the teacher's only victim. Under police investigation, he voluntarily admitted to other acts of molestation involving three other girls, aged 10 to 15.

The teacher cannot be named to protect the identities of his victims, whom he sexually abused between 2005 and last year. He was jailed for 30 months on Wednesday.

But it appeared that his propensities may have involved more underage girls, the court was told last month when he pleaded guilty to three charges. Two other charges were taken into consideration.

He had told Dr Stephen Phang, a senior consultant psychiatrist from the Institute of Mental Health, that he had hugged and kissed six other students between 2004 and last year, said Deputy Public Prosecutor Elizabeth Lee.

It was during his undergraduate days that he became acquainted with teenage girls through the Internet. He paid them a fee to be allowed to hug, fondle and caress them.

Dr Phang described the man as having significant hebephilic tendencies, a term describing a sexual preference for pubescent youths. He should not be employed in any profession which could potentially bring him into contact with adolescents, he added.

The man has since lost his job.

It was the first victim who blew the whistle on him, DPP Lee told District Judge Hamidah Ibrahim. In April last year, she had text messaged the man, her form teacher, after she was chided by her mother for not completing her homework in April last year.

He asked her to meet him in school the next day. When she turned up, he told her to leave her school bag in a room and led her to a male staff toilet.

He said he liked her, pulled her into the staff toilet and started hugging and kissing her.

Read the full story in Thursday's edition of The Straits Times.