Brazil's oil regulator ANP authorised state-run oil firm Petrobras to resume drilling activities at the environmentally sensitive Foz do Amazonas region on Wednesday, a document seen by Reuters showed.
The drilling was put on hold by ANP early last month after a synthetic fluid leaked from auxiliary lines connecting Petrobras' drilling rig to a planned well located off the coast of Brazil's Amazonian state of Amapa, in the northern part of the country.
The leak led to outcry from activists and local Indigenous organisations, who have for years warned of the impact oil exploration could have on the region's marine and coastal ecosystems.
Petrobras did not immediately reply to a request for comment.
Petrobras spent years trying to obtain a licence to drill in the region, considered to be its most promising oil frontier due to its shared geology with nearby Guyana where Exxon Mobil is exploring vast oil fields.
(Reporting by Fabio Teixeira and Rodrigo Viga Gaier, Editing by Iñigo Alexander and Nia Williams)