A man has been arrested following an assault outside a Christchurch carwash

A man's in a critical condition, after a driver of another car allegedly stabbed him at the intersection of Clarence Street and Blenheim Road just after 5.30 yesterday afternoon.

The vehicles were stopped at red lights when the incident unfolded - the victim was in the backseat.

The 26-year-old will appear in court tomorrow, charged with wounding with intent to cause grievous bodily harm.