SINGAPORE - A teenager has admitted molesting three girls on MRT trains.

Loh Kuang Guan, 17, admitted four offences on Tuesday, dating back to 2012 when he was just 14.

The court heard that in one instance in January that year, he kept bumping into a 19-year-old girl who boarded a train at City Hall station before putting his hand between her thighs. He eventually fled at Bugis station after the girl shouted at him.

An Institute of Mental Health report, cited by Loh's lawyer, said his client had struggled to control his sexual impulses, adding that he was remorseful for what he had done.

Deputy Public Prosecutor Jason Chua pointed out that the offences had been committed on four separate occasions, and not on the spur of the moment. He added that Loh went on to molest another victim on two separate occasions in March last year - even though police investigations against him had started in 2012.

Community Court Judge Mathew Joseph called for a pre-sentencing report on Chua's suitability for both probation and reformative training.

Loh is expected to be sentenced on Dec 9. The penalty for using criminal force to outrage modesty is a jail term of two years, a fine, caning, or any two of these punishments.