Oil major BP has sued the US state of Louisiana in a bid to block its order to remove metal anchors in waters that were used to hold down oil spill booms after the Gulf of Mexico disaster.

In the lawsuit, filed in US District Court in Baton Rouge, BP alleged that the Louisiana Department of Natural Resources' (DNR) order violates the federal prohibiting retrieval of the so-called "orphan anchors".

An explosion on BP's Deepwater Horizon rig on 20 April 2010, which killed 11 workers and sent more than 4 million barrels of oil into the sea, resulted in one of the worst environmental disasters in history.

Following the oil spill, BP dropped anchors throughout the Gulf to contain lines of spill booms under the direction of the US government. Many anchors were removed after the spill cleanup, but some of those anchors that were lost or buried, were eventually abandoned.

The US Coast Guard has said earlier that retrieving the abandoned anchors would hurt the environment in the Gulf of Mexico.

Meanwhile, Department of Natural Resources Secretary Stephen Chustz defended Louisiana's demand, saying that the anchors pose a safety risk.

"These anchors are abandoned, serve no purpose in the clean-up efforts now and are hazards to navigation and boaters," he said.

"Because of these public safety threats, DNR ordered BP to remove the anchors based upon authority granted to the agency under the Coastal Resource Management Act."

Litigations and Costs

BP has filed more than a dozen motions in the US courts related to the clean up and costs related to the spillage, after it made a settlement with the US government to compensate people harmed in the disaster. The company has since forked out $42.4bn (£26.45bn, €31.3bn) in oil spill related charges.

BP had complained that the claims administrator has been mismanaging settlement, increasing its costs. It repeatedly asked a US court to halt compensation payments due to the mismanagement, but the court ruled that there was no "credible evidence of fraud" in the compensation process as claimed by the oil major.

BP has also filed a lawsuit against the US government after it was barred from bidding for new federal contracts to supply fuel and other services as well as for leases to explore and drill in the Gulf.

The second phase of the main trial which will consider the amount of oil spilled to assign damages is scheduled to start on 30 September.

Cancellation of Project in Gulf of Mexico

Separately, Reuters reported citing three industry sources familiar with the decision that BP has cancelled contracts to build a bespoke extension to its Mad Dog oil project in the Gulf of Mexico.

The decision comes after the company reviewed the project amid rising exploration costs and uncertainty about future oil prices.

BP had planned to start construction of Mad Dog Phase 2 by the end of 2013 with estimated projects costs of more than $10bn.