US regulators on Wednesday hit British oil giant BP with five more citations for violations of rules that led to the catastrophic Gulf oil spill.

The Bureau of Safety and Environmental Enforcement (BSEE) issued a second list of violations regarding BP's operation of the Macondo well that blew out in April 2010, causing the worst maritime environmental disaster in history.

The US drilling safety agency said that it determined BP had failed to conduct an accurate pressure integrity test in one area of the well.

And in four different sections of the well, BP failed to suspend drilling operations at the Macondo when the safe drilling margin was not maintained, the agency said.

"Our federal regulations exist to ensure safe and environmentally responsible activities. We will continue to be vigilant in enforcing those regulations," the head of the BSEE, James Watson, said in a statement.

"Further review of the evidence demonstrated additional regulatory violations by BP in its drilling and abandonment operations at the Macondo well."

BP said it would appeal the latest citations as well as others recently issued.

"The issues raised in today's (citations) regarding drilling margins and related integrity testing played no causal role in the accident," the British company said in a statement.

An explosion at the Deepwater Horizon rig on April 20, 2010, killed 11 people, and the well gushed oil into the ocean for 87 days, blackening the southern US shoreline and crippling the local tourism and fishing sectors.

By the time the well was capped, 4.9 million barrels (206 million gallons) of oil had spilled out of the runaway well 5,000 feet (1,500 meters) below the surface of the Gulf of Mexico.

In October the US government slapped BP, Transocean -- the Swiss owner and operator of the drilling rig -- and US oil services group Halliburton with citations for violating oil industry regulations in what is expected to lead to massive fines.

BP -- which leased the rig and was ultimately responsible for operations -- has spent more than $40 billion on the disaster and could still be liable for billions in fines, compensation and restoration costs.

In October, it recovered $4.0 billion in costs associated with the spill from US group Anadarko Petroleum Company, which agreed to transfer its 25 percent stake in the well to BP.