NANJING - An 18-year-old boy in China was arrested on Monday (Aug 14) for molesting a child, later revealed to be his adopted sister, in a railway station.

Nanjing Railway Police was alerted to the case after photos of the boy groping the girl's chest as she sat on his lap went viral online, local media reported.

The incident took place last Saturday at about 7pm in the waiting hall of Nanjing South Railway station.

The boy's parents were also present at the railway station, although it is not clear if they were there when the obscene act happened, or whether they had stopped their son.

He was arrested in Henan's Hua County after investigations.

Police said the boy remains in custody, and that local authorities are looking for a better home for the girl, who is below the age of 14.

It is also looking at possible legal proceedings against the victim's adoptive parents.

Because the case concerns an underage child, the police urged netizens to stop sharing the photos so that the victim's privacy can be protected.