Mexican President Felipe Calderon says the country's state-owned oil company has made its first large-scale discovery of deep-water oil deposits in the Gulf of Mexico.

Calderon says Pemex drilled a roughly three-mile (5,000-meter) exploratory well and now hopes to verify the existence of 250 million to 400 million barrels of light oil in the area known as Perdido. The field is about 24 miles (39 kilometers) from U.S. waters.

Calderon says a deposit of that size would be equal to a third of Pemex's annual petroleum production.

The president made the announcement to reporters Wednesday.