The scale of BP's potential legal bill for the Gulf of Mexico oil spill has soared after the company disclosed $34bn (£22bn) of new claims by four southern US states.
The latest claims, presented to BP last month, mean the total cost of the spill to the company could be close to $50bn more than it has budgeted for.
BP is understood to have set aside a few billion dollars, at most, to cover the southern states claim and just $3.5bn for the Clean Water Act, which could result in a penalty of $21bn.
Analysts expect the eventual shortfall to be far lower than this worst-case scenario, but say the latest claims inject a significant further uncertainty into the legal proceedings.
BP revealed the claims as it announced that charges and divestments relating to the oil spill continued to take their toll on its bottom line last year, forcing profits down by 19 per cent to $17.6bn.
BP also said it was in discussions with Rosneft about working together inside and outside Russia following the $28bn sale of its 50 per cent stake in TNK-BP to the Russian state-owned oil giant in a cash-and-shares deal that left it with about a fifth of Rosneft's shares.
Bob Dudley, BP's chief executive, is talking to Rosneft about the Russian Arctic and pledged to proceed in the environmentally sensitive region "with great sensitivity and care". Outside Russia, analysts suggested Venezuela would be high on the agenda, where Rosneft already has a strong presence.
The claims which BP disclosed have been lodged by the states of Alabama, Mississippi, Florida and Louisiana. They seek to recover alleged losses including economic and property damage as a result of the explosion on the Horizon rig in April 2010 that resulted in 11 deaths and spilled an estimated 5 million barrels of oil into the Gulf.
The latest so-called economic restoration claims are separate from the $11.7bn BP has already spent on individual, business and government entity claims and other payments.
Instead, they have been made by states and mainly relate to tax revenues that have been lost as a result of companies that were forced to suspend or close down their operations and associated job losses. BP estimated that the total cost of the oil spill to BP would be $42.2bn, including legal, clean-up and other expenses.
A BP spokesman said of the latest claims: "The amounts claimed...are very substantial. However, BP considers the methodologies used to calculate these claims to be seriously flawed, not supported by the legislation and to substantially overstate the claims. Should these claims proceed to trial, we will defend vigorously against them."
Although BP has settled many of the cases against it, the biggest of all is still set for February 25 in New Orleans. BP said it continued to work towards a settlement over the civil case "but only on reasonable terms" and that it "continues to prepare for the civil trial".
If the case goes ahead, it will cover the state economic restoration claims, damage to natural resources and the Clean Water Act. If BP is found to have been negligent, it could be liable for a maximum penalty of $4.5bn from the Clean Water act alone. If grossly negligent, that number could soar to $21bn. BP is insisting that it was not grossly negligent.
Off-target: BG sends a production alert
BG Group, the former exploration arm of British Gas, has warned it would not hit its production target of more than one million barrels of oil equivalent a day by 2015.
It said production could actually fall this year as shutdowns and maintenance on key oil and gas fields threaten to drag on. It blamed missing the target on the sale of a stake in an Australian liquefied natural gas project to China's Cnooc.