Oil giant BP has fired the latest shots in a legal battle over the Deepwater Horizon catastrophe, claiming contractor Halliburton should pay all of its billions of pounds of costs.
In a filing at the federal court in New Orleans, BP said the cement contractor should reimburse it for the cost of cleaning up the oil spill, the lost profits from the well and "all other costs and damages", Bloomberg News reported.
BP has so far paid 21 billion US dollars (£13.5 billion) for the clean-up operation and compensating individuals, businesses and governments.
It has also reserved more than 40 billion US dollars (£25.8 billion) to cover costs related to the sinking of the Deepwater Horizon drilling rig.
BP and Halliburton accuse each other of making critical mistakes that caused the blow-out of the well off the Louisiana coast in 2010.
The disaster killed 11 workers and caused millions of gallons of oil to be leaked into the Gulf of Mexico, killing wildlife, polluting waters and shattering fisheries and tourism along the coasts of Texas, Alabama, Louisiana, Mississippi and Florida.
BP owned the lease for the Macondo well and Halliburton provided well-completion services for the project.
They are believed to jointly face more than 500 lawsuits by coastal property owners, businesses and governments claiming billions of dollars in damages.
A judge at a federal court in New Orleans is expected to begin a trial in February to determine liability for the spill.
Halliburton, based in Houston, Texas, has said its cementing services contract requires BP to indemnify it from all damage claims, even if its employees were found to have shared blame for the disaster, according to Bloomberg.
But BP has rejected that argument and has accused Halliburton of gross negligence.
The defendants in the lawsuits over the spill also include Switzerland-based Transocean - the owner of the Deepwater Horizon, Cameron International - the maker of the blow-out prevention equipment, Anadarko Petroleum, which owned 25% of the Macondo prospect, and Mitsui & Co's Moex Offshore unit, which owned a 10% stake in the well.
Cameron, Anadarko and Mitsui have already reached settlements with BP.
Before the disaster, BP was the biggest company in the FTSE 100 Index, and its leading payer of dividends.