RPT-UPDATE 1-"Anomaly" likely to delay BHP's Neptune oil field

(Repeats story from late Monday)

NEW YORK, March 24 (Reuters) - An unspecified "anomaly" discovered on the hull of the 50,000 barrels per day Neptune oil platform in the U.S. Gulf of Mexico will likely delay the planned end of March start-up of the field, a spokeswoman for operator BHP Billiton (BHP.AX: Quote, Profile, Research) said.

A routine inspection of of the hull Neptune tension leg platform turned up the structural anomalies last week, said BHP spokeswoman Teresa Wong.

"We are working on fully assessing the situation and are doing round the clock analysis," said Wong, who declined to elaborate on the nature of the problems discovered.

The anomaly is the latest setback for the U.S. offshore oil industry that has seen huge projects delayed by problems with new platforms.

BHP evacuated all personnel from the facility after the problem was discovered but has since determined Neptune is safe enough to allow work crews to return.

Neptune is located approximately 120 miles (190 km) off the coast of Louisiana in the Green Canyon area of the U.S. Gulf of Mexico.

BHP owns a 35 percent stake in Neptune, which is also expected to produce 50 million cubic feet per day of natural gas when it begins operations.

Marathon Oil (MRO.N: Quote, Profile, Research) holds a 30 percent interest in the project. Australia's Woodside Energy (WPL.AX: Quote, Profile, Research) owns 20 percent and the remaining 15 percent stake is held by a unit of Spain's Repsol-YPF (REP.MC: Quote, Profile, Research). (Reporting by Robert Campbell; Editing by Marguerita Choy)