Reports a man has been stabbed and had his car stolen by a group of people in north Christchurch.

Police were notified by St John just after 5am after they were called to a Richmond address.

A police spokeswoman says the alleged assault happened about two-hours earlier, 16 kilometres away in Kaiapoi.

She says they're not sure how the man got to Richmond.

The man was taken to Christchurch Hospital's emergency department, though the extent of his injuries are unclear.

Police are investigating.