A UK-based lobby group is calling for more transparency in the spending of global development aid, estimated to be worth about $150bn (£93bn).
Publish What You Fund says taxpayers in rich donor countries and recipients in poorer nations need more information to know if aid is being spent wisely.
It has published a transparency index ranking the openness of donor nations and organisations.
Major donors including the US, Japan and France score badly on the index.
The international development industry is big business - roughly equal to the value of the loan package currently being proposed to bail out Greece.
This official government aid, whether direct or through multinational organisations like the United Nations, is far larger than the amount distributed by charities such as Oxfam or Christian Aid.
But Publish What You Fund says the effectiveness of official aid, which is supposed to reduce poverty, is undermined by a lack of transparency in the way it is spent.
Almost the only information available about the large French aid programme in Ivory Coast, for example, related to a project commemorating 20 years of research into chimpanzees.
The organisation judged to be most transparent is the World Bank, which provides loans for development projects across the world.
Close behind at the top of the table were the multinational Global Fund, which supports work against infectious diseases, and the African Development Bank.
By contrast, the worst performing countries in terms of aid transparency were Greece, Cyprus and Malta.
The transparency index says Greece provides no information about its current aid activities - but that a two-year-old report did show pictures of a half-built block of flats in Serbia as an example of a project that had been implemented.