ExxonMobil Corp is studying a possible purchase of production rights in Brazil's so-called transfer-of-rights area - one of the world’s most promising offshore oil areas - although no decision has yet been made on the matter, an executive said on Friday.

Speaking at an event in Sao Paulo, Exxon's Brazil chief Carla Lacerda said the oil major was discussing the matter internally.

"It's a unique opportunity for the sector," Lacerda said.

"We're analyzing it, like other companies. There are uncertainties. An internal debate is going on," she said, without elaborating.

The transfer-of-rights area is a roughly 2,800-square-km (1,080-square-mile) zone off the coast of southeastern Brazil where billions of barrels of oil are trapped under the ocean floor.

After largely resolving a years-long dispute with state-run oil firm Petroleo Brasileiro SA in recent months, the government scheduled an auction of production rights in the zone for October.

Petrobras, as the firm is known, had already conducted significant exploratory work in the zone, making it a relatively low-risk asset and boosting its desirability to bidders.

Exxon has grown rapidly in Brazil in recent years. The firm has a stake in 26 offshore oil blocs in the nation, up from two just over a year ago.

(Reporting by Ana Mano; Writing by Gram Slattery Editing by Marguerita Choy)