RIO DE JANEIRO, March 11 (Reuters) - Brazil's Petrobras

has obtained approval from the country's

environmental agency to clear corals from the underside of the

drilling vessel it plans to use in the Foz do Amazonas region,

documents seen by Reuters showed.

The firm's February 10 request was granted on Monday for the

vessel the state-run firm will send to drill off the coast of

the northern Amapa state if it obtains a long-sought license to

explore the environmentally sensitive region.

Due to the corals being a potentially invasive species if

moved to another biome, it must be cleared in a process

supervised by Ibama, Brazil's environmental agency.

Once the corals are cleared in Rio de Janeiro, the vessel

could sail to the so-called Equatorial Margin, considered the

most promising frontier for oil exploration by Petrobras.

If the license is granted, Petrobras still hopes to begin

drilling this year.

Last month, Petrobras faced another setback to its plans to

drill in the area, as Ibama's technical staff recommended the

body deny the drilling license for a well in the northern end of

the Equatorial Margin, which shares geology with nearby Guyana,

where Exxon Mobil ( XOM ) is developing huge fields.

On Tuesday, Petrobras' exploration and production head

Sylvia dos Anjos said at the CERAWeek conference in Houston that

the firm is "optimistic" it will get the license.

In May 2023, Ibama denied Petrobras' request for an offshore

drilling license for the Foz do Amazonas area off the coast of

Amapa state, citing environmental concerns. The oil company

appealed soon after and a final Ibama decision is pending.