The Auckland man who lost three family members in a horrific house fire last month won't be able to attend their funeral.

Refugee Council secretary 47-year-old Kailesh Thanabalasingham is still critically injured after escaping the blaze in Flat Bush.

The fire claimed the lives of his 5-year-old son, 39-year-old wife and 66-year-old mother-in-law.

Family spokeswoman Deborah Manning said he's still in a critical condition, and not awake.

Ms Manning said it's extremely sad he won't make the funeral.

The public farewell service will be held at the Manukau Memorial Gardens on Thursday.