A house fire in Auckland in which a father and son died was non-accidental, police say.

Senior Sergeant Nadene Richmond, of Waitematā CIB, said: "Police can now confirm that following a number of inquiries, it's been established that the cause of the fire was non-accidental."

However, no one else is being sought by police in relation to the incident.

Police last week named father and son Lee Roycroft, 42, and Phoenix Roycroft, 13, as the two people who died in the blaze last Tuesday.

Two people died in the fire at a property in Coatesville last week. (Photo / Brett Phibbs)

Fire and emergency services were called to Māhoenui Valley Rd just before 6.30am. However, the pair died at the scene.

Police said they are continuing to support the family involved. They are also receiving help from Victim Support staff.