Police investigating the attack on New Zealand cricketer Jesse Ryder have made an arrest.

The 28-year-old is in hospital in an induced coma after suffering a serious head injury when four men set upon him in what has been described as an "unprovoked" assault.

A 20-year-old man has been charged with assault in connection with the incident and is due to appear in court on April 4, while a second suspect is close to being identified.

"Last night police interviewed a 20-year-old male in relation to their involvement in the initial altercation with cricketer Jesse Ryder," a police statement read.

"This person has been arrested and charged with assault and will appear in the Christchurch District Court on Thursday, April 4.

"Police are following a positive line of inquiry in relation to another person. Police are waiting for an update from Christchurch Hospital on Mr Ryder's condition."

Ryder, who has played 18 Tests and 39 one-day internationals for his country, recently signed a lucrative contract for Delhi Daredevils in the Indian Premier League.