SAO PAULO, Oct 20 (Reuters) - Brazil's environmental

agency Ibama greenlit state-run oil company Petrobras

to conduct exploratory research by drilling well in the Foz do

Amazonas region, near the mouth of the Amazon river, the firm

said in a statement on Monday.

The drilling is expected to begin immediately and last

around five months, Petrobras said, adding that for the moment

they will not be producing any oil.

The area, in deep waters off the shore of the Amazonian

state of Amapa, is considered Petrobras' most promising oil

frontier, sharing geology with nearby Guyana, where Exxon Mobil ( XOM )

is developing huge fields.

Petrobras is aiming to obtain more geological

information through the exploratory research and assess whether

there is oil and gas in the area on a commercial scale, it said.

As part of its bid to drill in the ecologically

sensitive region, Petrobras conducted an

emergency response

test in August to assess its preparedness.

Last month,

documents showed

that Petrobras had failed one part of the test, and was

demanded to resubmit its animal-rescue plan.

In Monday's statement, Petrobras said it had met the

requirements established by Ibama, "fully complying with the

environmental licensing process."

Petrobras' CEO Magda Chambriard celebrated the granting

of the license in a statement, calling it an "achievement for

Brazilian society."

"We hope to obtain excellent results in this research

and prove the existence of oil in the Brazilian portion of this

new global energy frontier," she said.

Ibama's decision comes as Brazil prepares to host the

global climate summit COP30 this November in the Amazonian city

of Belem, where Brazil is expected to call on the international

community to accelerate the shift away from fossil fuels.

The contrast between Brazil's energy policies and its

climate leadership ambitions have drawn sharp criticisms from

environmental advocates.