Germany and Japan have challenged new draft global anti-corruption guidelines for exporting companies, according to documents seen by the BBC.
There are fears that anti-bribery rules may be delayed
The countries say that rules aimed at improving the transparency of export credit agencies are too bureaucratic.
Tough new guidelines are being drawn-up by the Paris-based Organisation for Economic Co-operation and Development.
Critics have argued that many agencies backing their national exporters do too little to prevent firms paying bribes.
At the Gleneagles summit in July last year, members of the G8 group of leading industrial nations called for a strengthening of anti-bribery requirements "for those applying for export credits and credit guarantees".
Export credit agencies provide guarantees for national exporters, and are often a key factor for companies doing business in countries where the risks are considered to be high.
The new draft OECD guidelines, which were expected to be agreed next month, are intended to follow on from a weaker action statement issued more than five years ago.
However, objections by Germany, Japan and a number of smaller countries have raised fears that a final decision on new anti-bribery rules could be delayed.
In a paper responding to the latest draft proposals, Germany said combating bribery in international business transactions remained a "priority issue".
But it warned against introducing stricter guidelines for credit export agencies that would "only additional bureaucratic burdens".
Germany said it opposed plans to require agents representing exporting companies in countries to disclose their identity when seeking export credits or guarantees.
"It is highly questionable whether their revelation is a proper tool for detecting bribery," the German submission said.
Anti-corruption groups claim that some agents, who act as consultants for exporting companies in countries where they do business, have received or passed on bribes in order to facilitate deals.
Japanese officials said they were "sceptical" about the need for agents' identities to be revealed.
Tokyo added that "excessive responsibilities or roles" should not be imposed on export credit agencies.