A report from Standard & Poor’s Ratings Services indicates the firm may take additional rating actions in connection with the oil spill in the Gulf of Mexico.

In early May, S&P revised its outlook on BP Plc, London (AA/Negative/A-1+) from stable to negative and its outlook on Anadarko Petroleum Corp., The Woodlands, Texas, (BBB-/Stable/—) from positive to stable.

The explosion of Zug, Switzerland-based Transocean Ltd.’s (BBB+/Stable/A-2) Deepwater Horizon drill rig caused the oil spill from the Macondo deepwater well. BP has a 65% working interest in the well, while Anadarko has a 25% working interest.

S&P credit analyst Paul Harvey says, “Potential financial liabilities arising from litigation and limiting and cleaning up the oil spill, the likelihood of increased regulatory scrutiny for all offshore operations in the Gulf of Mexico, and the potential reputational damage for the companies involved in the incident are key factors behind our recent outlook revisions.”

Operational and estimated environmental cleanup costs, which could exceed $3 billion, constitute the immediate financial risk to the companies’ credit profiles, notes S&P. Costs and damage will continue to mount until the spill is controlled.

In S&P’s view, potential non-environmental liabilities could pose longer-term risks to BP, Anadarko and Transocean’s credit profiles. Included are potential litigation from business or property damage, escalating insurance premiums, and the likelihood of increased costs due to ensuing greater environmental and safety standards.

The companies can also face liabilities concerning longer-term environmental impact on the U.S. Gulf Coast’s fisheries and other habitats.

Harvey says, “We currently believe the companies involved should be able to fund the estimated near-term cleanup costs at current rating levels given their strong liquidity and our expectations for solid cash flows because of favorable crude oil prices. However, if the spill affects the shores of the Gulf region, we believe it is likely that the environmental remediation costs and litigation would escalate and have a negative impact on the credit profiles of the companies.”