23yo man arrested over death of Kiwi-born policeman Matt Ratana

NZ-born cop Matt Ratana was shot and killed at Croydon Custody Centre. Photo / File

A 23-year-old man has been arrested in relation to the murder of New Zealand-born policeman Matt Ratana in the United Kingdom.

The man has been accused of shooting the 54-year-old Metropolitan Police officer at Croydon Custody Centre in the early hours of September 25.

Ratana was taken to hospital but later died from his wounds.

Metropolitan Police say the accused had been arrested for a separate offence and was detained by officers at Croydon Custody Centre and then taken by ambulance to hospital with a gunshot wound.

No police firearms were discharged during the incident, they said in a statement.

"The man's condition, originally critical, has since stabilised and is no longer considered life-threatening," Metropolitan Police said.

On Friday, November 13 (UK time), the man was arrested on suspicion of murder, Metropolitan Police said.

In September, the man suspected of shooting Ratana was identified as Louis de Zoysa.

Matiu Ratana's family said they were devastated by his tragic death. Photo / Supplied

"However, as the man remains in hospital, officers will liaise with the relevant medical and legal teams to make an assessment of when he will be fit for interview."

Metropolitan Police said specialist family liaison officers from the Met's Specialist Crime Command are in regular contact with and supporting Matt's partner, his son and wider family.

The family have been told of the arrest.