A student from Nanyang Technological University (NTU) preyed on an underage girl and coerced her into having unprotected sex with him.

He even became her relief teacher later.

On Tuesday, the 25-year-old, who cannot be named due to a gag order, was sentenced to two years' jail after pleading guilty to three counts of sexual penetration of a minor.

Another eight charges relating to the acts were taken into consideration.

He has since filed an appeal and is currently out on $20,000 bail.

The accused met the 13-year-old victim in 2017, when they were both volunteering at a primary school.

They exchanged contacts during a band session and began contacting each other on social media around April that year.

He later sent her an obscene image of himself, and asked her to do the same.

The victim complied.

They met up on April 25, 2017, and went to the undergrad's home, where they engaged in sex acts after he had persuaded her to.

They met again two days later, this time at the undergrad's hostel, again engaging in sex acts while watching Fifty Shades Of Grey, an R21 movie.

On May 5, 2017, they went to the undergrad's home again, and the accused coerced her into having unprotected sex.

Weeks later, he began working as a relief teacher at the girl's school.

DELETED CHAT LOGS

When he began teaching her class, she confided in friends that they had had sex.

She informed her form teacher about the acts in July that year, and the teacher told her parents.

A police report was lodged on July 7, 2017.

When confronted by the head of department and school principal, the accused denied the allegations.

He also deleted their chat logs and photos as he did not want to risk them being circulated.

Deputy Public Prosecutor Sruthi Boppana urged the court to jail him for at least 33 months, saying he had been fully aware the victim was underage.

District Judge John Ng sentenced the undergrad on Tuesday, and later approved the application to stay the execution of the prison sentence pending the appeal.

Responding to media queries, an NTU spokesman said it takes a serious view of any criminal conduct by its students, who may be suspended or expelled as a result.

However, it added it was unable to comment on this specific case due to confidentiality reasons.

For each count of sexual penetration of a minor under 16, the undergrad could have been jailed for up to 20 years, and fined and caned.