By Brian Baskin Of DOW JONES NEWSWIRES NEW YORK (Dow Jones)--Transocean Inc. (RIG) is disputing that the U.S. drilling moratorium allows oil companies to prematurely end offshore rig leases, the driller said in its monthly fleet-status report. At least three oil producers have said they are invoking force majeure on their drilling contracts in the Gulf of Mexico, claiming that a six-month drilling moratorium will prevent them from using the rigs. Transocean operates two of the five rigs affected by the declarations, which are typically made when an outside event, such as a hurricane or war, prevents drilling. President Barack Obama announced a six-month halt to offshore drilling on May 27, more than a month after a Transocean rig caught fire and sank in the Gulf. Oil has gushed ever since from the BP PLC (BP) well that the rig was drilling. Both Anadarko Petroleum Corp (APC) and Statoil ASA (STO) have declared force majeure on Transocean rigs. Transocean joins Noble Corp. (NE) in publicly protesting force-majeure declarations. "We don't believe force majeure exists as a result of this drilling moratorium," said Guy Cantwell, a Transocean spokesman. "We're working closely with our customers on each situation." The contract with Anadarko leased the Discoverer Spirit rig for over $500,000 a day through November 2013. Statoil is leasing the Discoverer Americas for $482,000 a day through October 2013. -By Brian Baskin, Dow Jones Newswires; 212-416-2453; [email protected] (MORE TO FOLLOW) Dow Jones Newswires June 15, 2010 17:06 ET (21:06 GMT)