The United States and the European Union have made little progress in talks to resolve a dispute over financing of the new superjumbo jet.
The A380 plane is being built by Airbus Industrie to challenge the dominance of the Boeing 747.
A senior US trade official called the week's talks "a useful exchange of views" but said serious differences remain. Discussions are expected to be resumed.
"We have not set a date for continuing these discussions, but be assured they will continue," the official said.
She said she was certain the incoming Bush administration would pursue the issue given the importance to the US economy of Boeing, America's biggest exporter.
President Bill Clinton used his last presidential meeting with French President Jacques Chirac and other EU leaders last month to press concerns about the union's financing arrangements for Airbus to develop the A380.
The United States is disturbed that the £1.7 billion in long-term loans EU governments are providing Airbus for the A380 project violate World Trade Organisation rules governing government subsidies.
European officials have warned that if Washington brings a WTO case against the financing plan it would respond with a case challenging subsidies various defence and space contracts the federal government has awarded Boeing.
Airbus is Seattle-based Boeing's only major rival in the market for commercial jets.