The deal had been approved without restrictions on Jan. 27 by Cade's General Superintendent Alexandre Cordeiro Macedo. Cade's top administrative council can still call for a review of the case, putting the matter to a vote.

In the appeal filed on Wednesday, prosecutors referred to "some omissions" in the decision made by Macedo when assessing the markets that would be affected, citing the regional aviation market, which uses aircraft with fewer than 100 seats.

Boeing has offered to pay $4.2 billion for 80% of Embraer's commercial jet division, which builds passenger jets in the 70- to 150-seat segment.

The appeal, seen by Reuters, was filed by Deputy Attorney General Samantha Dobrowolski. Under Brazilian antitrust law, it will be now be assigned to a reporting commissioner who will decide whether it should be considered by the body.

The reporting commission's opinion on the appeal will then submitted to Cade's top administrative council, which will decide whether to review the case.

(Reporting by Ricardo Brito; Writing by Ana Mano, Editing by Franklin Paul)