A secondary school teacher who believed that one of his underage female students had a crush on him flirted with the 15-year-old girl before hugging and kissing her 10 days later.

The pair later started seeing each other, during which he pressured the minor to be physically intimate with him.

He became verbally abusive when she did not give in to his requests, and even told her she deserved to be raped when she did not want to go out with him.

The 34-year-old Singaporean man pleaded guilty to three counts of committing indecent acts on the girl and was sentenced to 17 months in jail yesterday.

His name as well as details about their school cannot be revealed because of a gag order to protect the girl's identity.

The man joined the school in 2016 and became one of the girl's teachers the following year.

She followed him on Instagram in January 2017, and they started messaging each other frequently via the platform after chatting on Aug 31 that year.

The pair met up on Sept 10, and he took the girl to the void deck of a block of flats where he hugged and kissed her. They then went to a nearby bench where he performed similar acts on her.

Deputy Public Prosecutor Deborah Lee said the man messaged the teenager via Instagram the next day to ask if she would accept him as her boyfriend.

She agreed on the condition that they would not do "anything that she was not comfortable with".

He sent her sexually charged text messages the following day, and kissed and hugged her again two days later.

On Sept 15 that year, he tried to pressure the girl into having sex with him. He hugged and kissed her when they met at a staircase that afternoon.

After this incident, the man frequently initiated conversations "of a sexual nature" with the girl despite her discomfort and attempts to change the subject.

She ended the relationship on Oct 14 that year as she felt guilty about being in a relationship with her teacher.

His offences came to light when the girl's mother checked the teenager's mobile phone and saw the messages that had been exchanged with the man.

The girl came clean about the relationship, and the police arrested the man soon after the school was alerted.