HOUSTON (Reuters) - BP Plc <BP.L> sued a Louisiana regulator on Thursday for requiring the company to retrieve anchors lost or buried during cleanup of its 2010 Macondo oil spill, even though the U.S. Coast Guard has said that would hurt the environment in the Gulf of Mexico.

The filing, in federal court in Baton Rouge, alleges that the Louisiana Department of Natural Resources ordered the company to violate federal law that prohibits retrieval of the anchors.

The anchors were dropped throughout the Gulf to hold lines of boom in place that were used to capture oil after the Macondo disaster that killed 11 men and sent more than 4 million barrels of oil spewing into the sea. BP said it deployed the booms as part of a U.S. government-directed spill response.

Many anchors were removed after the cleanup, but others lost or buried were left.

BP said the company cannot comply with Louisiana's demand that it recover the rest because federal law prohibits retrieval of so-called "orphan anchors."

The filing on Thursday was the latest of more than a dozen motions or appeals BP has made over the cleanup or to slow payouts from a 2012 settlement to compensate people harmed by the spill.

BP has complained that the settlement, which was not capped, has been mismanaged by the claims administrator and it is costing the company more than expected.

The company has also sued the U.S. government after the company was excluded from bidding for new federal contracts, including leases to explore and drill in the Gulf.

The Macondo disaster, the worst-ever offshore oil spill in U.S. history, so far has cost BP about $42.4 billion (26.45 billion pounds) in charges on its balance sheet from payouts, cleanup and restoration costs and ongoing litigation.

Separately, the second phase of the main trial over liability for the Macondo spill is scheduled to start September 30.

The first phase of the trial was held to determine blame for the spill, although the federal judge overseeing the case has reserved his findings. The second phase of the trial will consider the amount of oil spilled to assign damages.

(Reporting By Terry Wade; Editing by Tim Dobbyn)