Christophe Legrand, tsunami programme director for Care in Aceh, told Third Sector about the scheme after Oxfam and Save the Children both suspended project work in order to launch their own internal investigations.
Care piloted the postbox system in the civil war-torn Aceh province last year, enabling those who were not receiving their food entitlements because of corruption to complain. The organisation is planning to expand the system to other projects.
When Oxfam discovered "financial irregularities" in one of its project offices, it issued a statement announcing that it had temporarily suspended part of its operations in Banda Aceh and Aceh Besar.
The charity has sent in auditors and put activities such as house-building on hold, although essential services, such as water deliveries and rubbish collections, will continue. It hopes to have resumed all work within weeks.
Save the Children issued a statement to the Indonesian media after it uncovered sub-standard workmanship in Aceh, including the use of untreated timber in construction programmes.
Construction has been postponed while Save the Children works to improve transparency and workmanship. But it has insisted that it caught the problem early and will rebuild those buildings that need it.
With corruption rife in the region, Legrand said charities were working together to ensure that aid work was carried out in a transparent and accountable manner.