Oil giant BP has been ordered to appear before a US court relating to the Prudhoe Bay oil spill in Alaska this year.
The US grand jury has issued the company with a subpoena following the March spill, in which over 200,000 gallons were leaked.
The news that the British firm was facing criminal court proceedings emerged when an email sent from the president of BP Alaska (BPXA), Steve Marshall, to staff was itself leaked to the Financial Times.
"BPXA will comply fully with the government in responding to the subpoena and with the grand jury investigation," the email said.
A spokesperson for BP has since confirmed that the company had been called before the courts, explaining that the firm will cooperate fully with US authorities and supply the relevant documents and data.
But in his original email, Mr Marshall explained that he believed the court proceedings would exonerate BP of any criminal charges.
"I believe that the information we provide will show that the actions of BPXA were, at all times, proper."
The Prudhoe Bay oil spill was the largest in the history of Alaska's North Slope, with BP attributing the pipeline leak to excessive corrosion.