Auckland police are trying to identify a man who allegedly indecently assaulted a high school girl on a bus today.

Another passenger on the number 18 bus on Great North Rd intervened in the incident and stopped the man.

About 8.40 this morning, a Herald reporter on the bus heard a passenger yelling “perv” and asking the driver to pull over. Another person was heard saying “you don’t treat women like that”, while another was heard sobbing.

After the man was kicked off, he stood outside and made an indecent hand gesture towards the bus.

Detective Senior Sergeant Martin Friend said the man got on at a stop near King St, in Grey Lynn.

“He sat down next to a high school student and [allegedly] touched her inappropriately,” Friend said.

“This was witnessed by a passenger, who quickly intervened and stopped what was taking place.”

The man got off near Maidstone St, Friend said.

The man police are seeking in relation to an alleged indecent assault on a route 18 bus on Great North Rd, Auckland. Photo / New Zealand Police

Friend hailed the actions of the witness.

“The witness did an incredible job in coming to the assistance of the student,” he said.

“We are aware that the witness and another passenger supported the girl and walked her safely to school.

“Our witness has also obtained a photo of the man we would like to speak with.”

The high schooler has been given “appropriate welfare” support after the incident.

Friend said police were confident the public would know this man and contact police.

People with information are asked to contact 105 and reference file number 250312/9531 or to provide it anonymously to Crime Stoppers on 0800 555 111.