“The final report is currently scheduled to be issued by the end of January. It’s the version that will still be confidential. We won’t see the public version for some time after that,” a spokeswoman for the office of the US Trade Representative said.

The EU complaint to the WTO is part of a long-running transatlantic spat over subsidies to the aerospace sector.

The ruling comes over a year after the WTO rapped the EU for illegally providing subsidies to plane-maker Airbus, a unit of the European Aeronautic Defence and Space Company.

An interim ruling on the EU case against Boeing was issued to the disputing parties in September but given its confidential nature, both parties were keen and free to spin their own version of events.

The EU claims that the WTO found billions of dollars in US aid to the aircraft manufacturer illegal, while Boeing in turn claimed that the WTO had issued a “massive rejection” of the European claims.

The end-January final ruling will also be confidential and not be made public until after it has been translated into the WTO’s three working languages. Given the highly technical nature of the report and its size, this process could take weeks, if not months.

The parties will also be able to appeal against the ruling after the report is published.