BP could face a multi-billion dollar fine after it was found to be “grossly negligent” over the 2010 Gulf of Mexico oil spill.

District Judge Carl Barbier of New Orleans reportedly ruled that BP should accept 67% of the blame for the disaster, with Transocean responsible for 30% and cement firm Haliburton bearing 3% of the responsibility.

The more serious ruling imposed upon BP means it could have to pay as much as $18 billion (£11bn) in penalty under the Clean Water Act compared to just $3.5 billion (£2.1bn) it has set aside so far for the fines.

The 2010 disaster killed 10 people and spewed oil for almost three months into waters that touch the shores of five states.

BP said it “strongly disagrees” with the ruling and will “immediately appeal” to the US Court of Appeals for the Fifth Circuit.

It added in a statement: “BP believes the finding that it was grossly negligent with respect to the accident and that its activities at the Macondo well amounted to wilful misconduct is not supported by the evidence at trial. The law is clear that proving gross negligence is a very high bar that was not met in this case.”

No penalty has yet been determined as the District Court is to hold additional proceedings, which are scheduled to start in January next year.