The US oilfields contractor Halliburton is suing BP in the US for "negligent misrepresentation, business disparagement and defamation" related to the Gulf of Mexico oil disaster last year, which killed 11 people and caused the worst offshore spill in US history.
The US group said the allegations were based on BP providing inaccurate information before Halliburton carried out cementing work the day before the Gulf of Mexico spill.
BP last night said it was reviewing the claims, but it believed the suit was "the latest attempt" by Halliburton to "divert attention" from its role in the incident. The oil giant said it would vigorously contest the claims in court.
In April, BP sued Halliburton and other contractors on the rig, demanding they shoulder some of the cost of the clean-up and compensation.