An Auckland teenager fighting for his life in hospital was stabbed and bashed on a Wanganui street because he was wearing a blue hat, the colour of a rival gang, his family says.

The 16-year-old had been on holiday in the city and staying with his sister when he was attacked on a street on Wednesday evening.

He was stabbed in the face and bashed across the back of the head. He was initially taken to Wanganui Hospital but was transferred to Wellington where he remains in intensive care.

Police were still trying to piece together what happened but a family spokeswoman said there had been an earlier incident between the youth's older brother and a "man in red."


Later the 16-year-old was riding his bike when he was attacked from behind.

"He was bashed across the back of the head then stabbed in the face."

She said the incident had been about "colours".

"It's so stupid ... the 16-year-old was wearing a blue hat which means he associates with Black Power".

The youth's family had driven from Auckland to Wellington Hospital, she said.

"He's pretty bad... we know that's why they sent him through to Wellington."

A 21-year-old man was arrested at the scene of the incident and is in custody to appear in court on December 11.

Another man is still being sought.