BRASILIA, June 19 (Reuters) - The head of Brazilian

environmental agency Ibama, Rodrigo Agostinho, said on Wednesday

that he expects a decision soon on state-owned oil company

Petrobras' request to conduct exploratory studies in

a region known as the Equatorial Margin.

Petrobras has been pushing for a license to drill in the

northernmost part of the Equatorial Margin, near the mouth of

the Amazon River, where scientists have warned of threats to

local coral and coastal biomes.

Brazilian President Luiz Inacio Lula da Silva has been

supportive of Petrobras' push to explore the region, saying the

country cannot give up such an opportunity.

The offshore region is seen as Brazil's most promising

frontier for oil exploration as it shares similar geology with

nearby Guyana, where Exxon Mobil ( XOM ) is developing huge

fields.

Ibama had previously denied a drilling license in the

area, citing potential impact on the environment and Indigenous

peoples.

Petrobras has been waiting about a year for it to rule

on an appeal.