A new "code of conduct" for consultants and others providing the Government with international development services has been published.
The move is designed to deal with the controversy over so-called "poverty barons" - individuals being paid large sums from the aid budget.
Two of the top earners are reported to command more than £200,000 a year each at a time when overseas spending is under pressure.
A Government commitment to maintaining funds to meet a target of spending 0.7% of national income on aid is controversial at a time of severe domestic spending cuts.
The code, which covers value for money, transparency and accountability, is voluntary but the Department for International Development (DfID) said the majority of its 12 biggest suppliers had signed up.