European aerospace giant Airbus expects the World Trade Organisation to rule that US rival Boeing received billions of dollars in illegal subsidies, a spokeswoman said on Monday.

Wednesday's interim WTO panel report could herald a negotiated settlement to the long-running dispute between the two companies over multi-billion-dollar government subsidies, with both sides filing rival complaints with the WTO.

"Airbus is looking forward to see the European Union case finally moving forward," said Airbus spokeswoman Maggie Bergsma. "We expect the WTO to confirm that Boeing received billions of illegal subsidies."

The WTO had been expected to issue its opinion on US subsidies to Boeing in July but it decided to postpone the release.

The delay disappointed the European Union, still smarting from the world trade referee's finding on June 30 that some of the EU's own subsidies to Airbus were illegal.

"Only with two reports on the table is there a window for a balanced discussion, which will be the only way out of this destructive and anachronistic dispute," Bergsma said.

The European Commission, the European Union's executive arm, has said the report on US aid was crucial to provide a "complete picture" of the dispute.