The US is suing oil giant BP Plc and eight other companies linked to the Gulf of Mexico oil spill for violating American environmental laws, Attorney General Eric Holder has said.

The civil suit was filed in the US District Court in New Orleans against BP, rig operator Transocean, Anadarko Petroleum Corp, Transocean's insurer Lloyd's and five others for their role in the spill.

The lawsuit asks for civil penalties under the Clean Water Act and to declare eight of the defendants liable without limitation under the Oil Pollution Act for all removal costs and damages caused by the spill, Holder said Wednesday.

"We intend to prove that these defendants are responsible for government removal costs, economic losses and environmental damages without limitation," Holder said.

"Both our civil and criminal investigations continue, and our work to ensure that the American taxpayers are not forced to bear the costs of restoring the Gulf area and its economy is moving forward."

The Deepwater Horizon rig exploded April 20, killing 11 oil rig workers and causing a well rupture that resulted in nearly 5 million barrels of oil spewing into the Gulf of Mexico, leading to the worst environmental disaster in US history. Oil continued to flow out of the well until July and it was finally plugged in September.

According to the suit, the defendants failed to keep the oil well under control in the period leading up to the explosion; failed to use the safest drilling technology to monitor the well's conditions; failed to maintain continuous surveillance; and failed to use equipment necessary to ensure the safety of both personnel and natural resources.

BP said in November that the cost of the oil spill had risen to $11.6 billion. Total costs are expected to reach about $40 billion, including $20 billion set aside for compensation payments in an agreement signed with the US government.