Abelardo Bayma Azevedo apparently refused to grant an installation licence allowing construction to begin on the 11GW hydro project, citing environmental concerns.
Azevedo took the helm last April after his predecessor also resigned over pressure to issue environmental licences for energy and infrastructure projects.
In late 2009, two other Ibama officials in charge of issuing the preliminary licence for Belo Monte quit, citing political interference to approve the project.
Américo