The US government said Wednesday it was suspending part of a WTO case against Europe over aircraft subsidies but insisted it was pressing ahead with the complaint as a whole.

The US Trade Representative's office (USTR) said it was now holding fire on a second complaint over European Union subsidies for Airbus, which the World Trade Organisation agreed to hear in May.

It will be kept back until a WTO panel rules on the first US complaint, which alleges that Airbus has benefited from billions of dollars in improper EU subsidies down the years to gain an unfair edge over US giant Boeing.

"The United States continues to support a negotiated solution that would end launch aid and other subsidies to Airbus," USTR spokeswoman Gretchen Hamel said in a statement.

"In the meantime, we are pressing ahead with our WTO case," she said.

The EU has counter-sued the United States at the WTO, alleging that Boeing has received its own share of subsidies indirectly from both federal and state authorities in violation of global trade agreements.