Awaab’s father, Faisal Abdullah, had repeatedly complained to RBH over the conditions of the flat but no action was taken, with the family reportedly told to paint over the mould.
An inquest into the child’s death in December 2020 heard how the bathroom had no window, the fan did not work effectively and the window from the kitchen, which had no mechanical ventilation, opened onto a communal hallway.
Mr Abdullah, a refugee from Sudan, had accused RBH of racism when it suggested the family’s bathing habits and cooking techniques had contributed to the build-up of dangerous fungus and mould.
RBH admitted on Tuesday it had made “false assumptions” about the family’s lifestyle when they raised complaints.
In a statement RBH’s board said: “We will be implementing further training across the whole organisation. We abhor racism in any shape or form and we know that we have a responsibility to all our communities.”