Police are appealing for help to track down a man after a serious assault on an elderly Christchurch couple.

Douglas James Archer, 59, of Christchurch is a male European, 175 centimetres tall and of thin build.

The police believe he has vital information about yesterday afternoon's assault, in which a 72-year-old man and his 80-year-old wife sustained serious injuries.

A neighbour found the woman bloodied and "dangling" over the fence, crying for help. She suffered broken knuckles and she had cuts across her face.

Her husband sustained serious head injuries.

Police said they believed the couple were attacked by a male relative who used a weapon.

The two remain in hospital in a stable condition, but have been traumatised by the attack. Police have spoken with the couple today to establish what happened.

Archer was believed to be driving a 1996 Honda Accord LXI sedan, with the registration number UJ7255.

Detective Sergeant Michael Ford said Archer should not be approached.

Anyone with information as to where he is should contact police immediately on (03) 363 7400.

- © Fairfax NZ News