Halliburton sues BP for defamation over Gulf spill

(Reuters) - Halliburton Co <HAL.N> is suing BP Plc <BP.L> <BP.N> for "negligent misrepresentation, business disparagement and defamation" related to BP's claims about who was to blame for last year's Macondo oil spill in the Gulf of Mexico.

Halliburton said BP provided inaccurate information prior to Halliburton carrying out its cementing services the day before the disaster, according to the lawsuit, which was filed in Texas state court.

Halliburton said BP knew or should have known about an additional hydrocarbon zone in the well and that the British company failed to tell Halliburton before it designed the cement program and then did not disclose it after the blowout.

"BP was solely responsible for identifying all hydrocarbon-bearing zones in the well and for identifying where the designed top of cement should be located in order to isolate all such zones," Halliburton said in the lawsuit.

BP said it was reviewing the lawsuit and so could not comment in detail, but it noted investigators had found multiple parties responsible for the accident, including Halliburton, and that independent investigations identified "serious problems" with the cementing of the well.

BP and Transocean Ltd <RIGN.VX> <RIG.N>, owner of the drilling rig that exploded and sank after the well blowout, are already locked in a legal battle over which company was at fault in the April 2010 disaster, which killed 11 workers and caused the worst offshore spill in U.S. history.

Halliburton, the world's second-largest oilfield services provider, said on Friday it had also moved to amend its claims against BP in separate litigation in New Orleans to include fraud.

The Houston-based company said it was fully indemnified under its contract with BP because it had performed the cement work according to BP specifications.

In April, London-based BP sued Transocean, Halliburton and Cameron International <CAM.N>. Cameron made the blowout preventer for the well, a so-called fail-safe device that failed to automatically shut down the well.

Shares of BP and Haliburton were both down 3 percent on Friday on the New York Stock Exchange. The S&P 500 index was about 2 percent lower.

The case is Halliburton Energy Services Inc v. BP Exploration & Production Inc et al, No. 2011-52580 in Court 234 of the District Court of Harris County, Texas.

(Reporting by Ian Geoghegan and Krishna N Das in Bangalore, and Braden Reddall in San Francisco; Editing by Gopakumar Warrier and Steve Orlofsky)