Irish police are investigating the disappearance and whereabouts of the boy, who would be seven years old if still alive, and last lived in an apartment in the Donabate area of Dublin.
A search of open ground began in Donabate this week after concerns for the boy were raised by Ireland’s child and family agency Tusla on Friday.
The agency had previously engaged with the missing child’s family five years ago.
Tusla’s chief executive has said there were no child protection concerns in the agency’s interactions with the boy’s family prior to the case being closed during Covid-19.
The matter has been referred to the independent National Review Panel (NRP) for investigation.
In a statement on Thursday, Ombudsman Dr Niall Muldoon criticised the response of the Government and Tusla.
He said