David M. Uhlmann, a law professor at the University of Michigan, said the filing had been expected. “The only question,” he said, “has been when, not if, a civil suit would be filed.”

Professor Uhlmann, who led the environmental crimes section of the Justice Department during the George W. Bush administration, called the filing “the opening salvo in the government’s response to the gulf oil spill.” Although the suit could subject BP and the other companies to billions of dollars in civil penalties and natural resource damage claims, he said the next act could be even more dramatic: a criminal case, he said, would “bring the most significant penalties and provide the most meaningful accountability for this tragedy.”

Scott D. Dean, a spokesman for BP, said the filing “does not in any manner constitute any finding of liability or any judicial finding that the allegations have merit.” The company, he said, will continue to work with the government, and he noted that BP had created a $20 billion fund to pay “all legitimate claims” from the spill, “before any legal determination of responsibility and will continue to fulfill our commitments in the gulf as the legal process unfolds.”

Transocean denied liability in a statement, saying that the company followed “calculations, blueprints and step-by-step construction procedures” from BP that federal regulators approved. Responsibility “lies solely with the well’s owner and operator,” the company said.

John Christiansen, a spokesman for Anadarko Petroleum, which owns 25 percent of the well, also placed the blame on BP in an e-mailed statement. He said that in the case of gross negligence or willful misconduct, the operating agreement between BP and the other owners places the liability with BP  and, he said, “the operator’s decisions and actions on the rig likely amount to gross negligence and/or willful misconduct.”

A spokesman for MOEX, which owns 10 percent of the well, said that the company was reviewing the filing, but added that MOEX “had no authority or responsibility to direct activities on the Deepwater Horizon.”

A member of Congress who has been sharply critical of BP applauded the lawsuit. Representative Edward J. Markey, a Democrat of Massachusetts, said: “It may have taken these companies months to cap their well, but they will spend years trying to cap their financial obligations to the people of the gulf.”