RIO DE JANEIRO (Reuters) - Brazilian investors' association Abradin has filed a motion with a São Paulo court questioning the legality of a tie-up between U.S. planemaker Boeing Co <BA.N> and Embraer SA <EMBR3.SA>.
The motion asks the court to determine whether Embraer shareholders should be eligible for a public tender offer. Abradin could bring legal action against the deal if a public tender is not launched.
"We understand that this is an illegal operation," Abradin's president, Aurelio Valporto, told Reuters.
Embraer's bylaws ensure an offer to all shareholders with a 50 percent premium over market prices if any investor buys 35 percent or more of the company.
Embraer and Boeing finalised a deal this week in which Embraer will sell 80 percent of its commercial jet unit, netting $3 billion in proceeds.
Both companies did not immediately comment on the matter.
(Reporting by Rodrigo Viga Gaier and Marta Nogueira; Writing by Gram Slattery; Editing by Frances Kerry)