A man was followed, robbed and beaten up by a group of teenagers in Brooklyn, Wellington, after he asked them to not smoke on the bus.

The victim, who wished to remain anonymous, was left bleeding heavily from a facial cut and taken to hospital.

He is now too afraid to go on the bus or visit Brooklyn.

On Saturday night while taking the bus to visit his girlfriend, the victim witnessed a group of teenagers board and then, later, smoke coming from the mouth of one person.

“I instinctively, blurted out something among the lines of ‘WTF dude, you can't smoke on the bus’.

“I was not trying to give offence to anybody.”

The victim, who later believed the teenager was vaping, was then harassed by members of the group, which included about 15 teenagers.

“I ignored them, and didn't say a word, kept looking at my phone.”

He got off the bus at the Brooklyn shops but, because he was wearing noise-cancelling headphones, he didn’t realise the group was following him.

He stopped on Cleveland St, near The Brooky bar, to send a text, and then found himself surrounded by the group.

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“I’m forced with my back against the wall to avoid being touched. They screamed at me ... three rows thick of teenagers had surrounded me by now.”

The victim was then punched in the face and fell to the ground, where he was kicked by members of the group, before they ran off.

His pair of $500 Sony noise-cancelling headphones were stolen in the assault and his phone was thrown to the ground, smashing the screen.

The victim believes the person who punched him was wearing a ring, causing a cut on his face which bled heavily and required four stitches.

The next night, the victim was “enraged” to be told the assault had been filmed and posted on social media.

“I'm still incredibly angry about this. Although, admittedly, given they were teenagers ... I'm not surprised.”

The Brooky bar owner Mark Kisby said staff members and customers came to the aid of the victim after the “pretty vicious” incident.

In his 10 years of owning the family bar, and 15 years of working in real estate in Brooklyn before that, he said he’d “never heard of anything like this before” in the neighbourhood.

A police spokeswoman said police conducted area inquiries, but did not locate the group.

“ Anyone with information about the incident or those involved should get in touch with police by calling 105, quoting file number 200830/8118.”

A Metlink spokesman said it was cooperating fully with police on its investigation.