In fact, such secrecy runs counter to international norms for foreign assistance. In a part of the world prone to corruption and poor governance, it also raises questions about who actually benefits from China’s projects. The answers, international development specialists say, are hidden from public view.

“We know more about China’s military expenditures than we do about its foreign aid,” said David Shambaugh, an author and China scholar at George Washington University. “Foreign aid really is a glaring contradiction to the broader trend of China’s adherence to international norms. It is so strikingly opaque it really makes one wonder what they are trying to hide.”

Until recently, wealthy nations could hardly hold themselves out as an example of how to run foreign aid, either. Many projects turned out to be tainted by corruption or geared to enrich the donor nation’s contractors, not the impoverished borrowers. But over the past 10 or 15 years, some 30 developed nations under the umbrella of the Organization of Economic Cooperation and Development (O.E.C.D.) have made a concerted effort to clean up their assistance programs.

They demanded that foreign money be awarded and spent transparently, using competitive bidding and outlawing bribery. Increasingly, they also are also pushing to give borrowers more choice among suppliers and contractors, rather than insisting that funds be recycled back to the donor nation’s companies.

China, which is not a member of the O.E.C.D., is operating under rules that the West has largely abandoned. It mixes aid and business in secret government-to-government agreements. It requires that foreign aid contracts be awarded to Chinese contractors it picks through a closed-door bidding process in Beijing. Its attempts to prevent corrupt practices by its companies overseas appear weak.

Some developing nations insist on independently comparing prices before accepting China’s largesse. Others do not bother. “Very often they are getting something they wouldn’t be able to get without China’s financing,” said Chris Alden, a specialist on China-African relations with the London School of Economics and Political Science. “They presume that the Chinese are going to give value for money.”