LONDON (AP) — BP PLC said Wednesday that it had made a “giant” oil discovery in the Gulf of Mexico but had not yet determined the size and commercial potential of the find.

The well, in Keathley Canyon block 102 about 250 miles (400 kms) southeast of Houston, is in 4,132 feet (1,259 meters) of water, the company said.

The Tiber well was drilled to a total depth of 35,055 feet (10,685 meters), making it one of the deepest wells ever drilled by the oil and gas industry, BP said.

BP has a 62 percent interest in Tiber, while Petrobras holds 20 percent and ConocoPhillips has 18 percent.

BP shares were up 1.9 percent at 529.5 pence on the London Stock Exchange.