(Reuters) - Italian energy group Eni has made a significant oil and gas discovery in the Sureste Basin, about 63 kilometres off the coast of Mexico, it said on Monday.

The discovery, in an exploration well called Block 9, has a preliminary estimate of 300-400 million barrels equivalent (Mboe) of oil and associated gas in place, the company said in a statement.

Eni and Spanish peer Repsol each hold a 50% stake in the Block 9 joint venture.

The find comes on top of other discoveries already made in other Eni-operated blocks in the area in the Gulf of Mexico.

"The overall estimate of resources in place currently exceeds 1.3 billion barrels of oil equivalent (Bboe) which allows Eni to advance with the studies towards a potential future hub development," Eni said.

(Reporting by Romolo Tosiani; Editing by Keith Weir)