a) The financial audit of projects is to be carried out by an independent auditor having the required professional competence and experience, and in accordance with generally accepted international auditing standards.
b) The auditor must not have been involved in the operation’s accounting.
c) The auditor must not personally be connected in any way with the organisation being audited.
d) The auditor must be a registered audit company in Ethiopia, a neighboring country or in the European Union.
You can get full description of the BID from the link below