WASHINGTON (AFP)--U.S. investigators have descended on New Orleans in a criminal probe into whether too-cozy ties between BP PLC (BP) and federal regulators contributed to the Gulf oil spill, the Washington Post reported Wednesday. The team of investigators dubbed the "BP Squad" includes officials from the Environmental Protection Agency, the U.S. Coast Guard and other federal agencies, sources told the Post. In addition to BP, other firms at the center of the inquiry are Transocean Ltd. (RIG), which leased the Deepwater Horizon rig to BP, and engineering giant Halliburton Co. (HAL), which finished cementing the well less than two days before the rig exploded April 20, the daily reported. The newspaper wrote that the investigation is in its early stages, with officials digging through tens of thousands of documents turned over by the firms, interviewing company officials and trying to determine who was responsible for various operations on the rig. Authorities also are looking into whether company officials made false statements to regulators, obstructed justice or falsified test results for devices such as the rig's failed blowout preventer, the daily said. The Post said it was told by sources that one line of inquiry is whether inspectors for the Minerals Management Service, or MMS--the federal agency charged with regulating the oil industry--went easy on the companies in exchange for money or other inducements. A series of federal audits has documented the MMS's close relationship with the industry. The probe is one of several currently underway into the worst environmental disaster in U.S. history, including a Justice Department investigation announced in June by U.S. Attorney General Eric Holder and state criminal probes in Louisiana, Mississippi and Alabama. The Post wrote that in another avenue of inquiry, BP revealed in a regulatory filing Tuesday that the Justice Department and the Securities and Exchange Commission are looking into "securities matters" relating to the spill, although no additional details were disclosed. Halliburton informed its shareholders about the Justice Department probe in its July 23 quarterly report to securities regulators, the daily wrote. The Post also wrote that the department warned the company not to make "substantial" transfers of assets while the matter is under scrutiny. (END) Dow Jones Newswires July 28, 2010 05:35 ET (09:35 GMT)