Anadarko Petroleum has debt downgraded in BP oil spill row

Anadarko Petroleum Corp had its long-term debt downgraded and Moody's Investor Services has placed its ratings under review for further possible action.

Anadarko attacked BP's "reckless decisions and actions" that led to the well's explosion, as chairman and chief executive Jim Hackett knocked back suggestions from US officials that the firm should help pay for the clean-up and oil damages claims.

The firm also criticised Moody's downgrade, which dropped the company's debt rating from Ba1 from Baa3.

"Although we understand the concern over uncertainty surrounding the current situation, we believe it is too early in the process for Moody's to take this action," said Anadarko's chief financial officer, Robert Gwin.

Hackett maintained that blame for the explosion on the Deepwater Horizon rig on April 20, which caused the leak, lay with BP.

"The mounting evidence clearly demonstrates that this tragedy was preventable and the direct result of BP's reckless decisions and actions," he said.

"We recognize that ultimately we have obligations under federal law related to the oil spill, but will look to BP to continue to pay all legitimate claims as they have repeatedly stated that they will do."

The information disclosed this week "indicates BP operated unsafely and failed to monitor and react to several critical warning signs during the drilling", a company statement said.

"BP's behaviour and actions likely represent gross negligence or wilful misconduct."

BP chief executive Tony Hayward said the company strongly disagreed with the allegations.

"These allegations will neither distract the company's focus on stopping the leak nor alter our commitment to restore the Gulf coast. Other parties besides BP may be responsible for costs and liabilities arising from the oil spill, and we expect those parties to live up to their obligations."

Anadarko had no employees on the well and was a non-operating partner in the project. The rig was owned by Transocean Ltd. of Switzerland and operated by BP. A subsidiary of Mitsui & Co of Japan had a 10% stake.

Anadarko also hinted at potential legal action against BP. Its statement said BP had a duty to perform the drilling "in a good and workmanlike manner and to comply with all applicable laws and regulations".