US government regulators cited oil giant BP and two other companies - Transocean and Halliburton - for alleged safety and environmental breaches stemming from last year's Gulf of Mexico rig explosion and massive oil spill.
The companies have 60 days to appeal against citations issued by the Interior Department's Bureau of Safety and Environmental Enforcement.
The bureau says the alleged regulatory violations could result in civil penalties once the appeal period has ended.
These initial citations are the product of a government probe of the Deepwater Horizon blast, which killed 11 workers and hastened America's worst offshore oil spill.
One of the citations accuses well owner BP, rig owner Transocean and cement contractor Halliburton of failing to operate in a "safe and workmanlike manner".