A young man has been charged with murdering a 3-month-baby and will appear in court later this month.

The infant died in Middlemore Hospital on April 13, after being assaulted at an address in Papatoetoe, Detective Inspector Shaun Vickers said.

The man, 21, was arrested following a homicide investigation, called Operation Searcy, by Counties Manukau Police.

As the matter was before the courts, police were unable to comment further.