WASHINGTON (Reuters) - Rolls-Royce Plc (>> Rolls-Royce Holding PLC) agreed to pay authorities more than $800 million to resolve charges of bribing officials in six countries in schemes that lasted more than a decade, the U.S. Justice Department and UK Serious Fraud Office said in statements on Tuesday.

The company admitted to paying officials at state-run energy companies in Kazakhstan, Thailand, Brazil, Azerbaijan, Angola and Iraq more than $35 million in order to win contracts, the Justice Department said.

In a statement, the company's chief executive officer, Warren East, apologized "unreservedly" for the bribery schemes. The company had since overhauled its compliance rules and cut back on using intermediaries, the statement said.

Among the bribes, Rolls-Royce paid a Brazilian official $1.6 million through a middleman to win numerous oil equipment contracts from Petrobras (>> Petroleo Brasileiro SA Petrobras), U.S. authorities said.

The case was the third resolution related to Petrobras in the United States following a nearly three-year investigation in Brazil dubbed "Operation Car Wash" into corruption at the oil company, which has led to dozens of arrests and political upheaval in the country.

Petrobras did not return a request for comment.

In Iraq, Rolls-Royce middlemen bribed Iraqi officials after they had expressed concerns about turbines the company had sold. The Rolls-Royce bagman paid the bribe to "persuade the officials to accept the turbines" and prevent the officials from "blacklisting" Rolls-Royce from future business in Iraq, U.S. authorities said.

The settlement included agreements with U.S., UK and Brazilian authorities whom the company agreed to pay $170 million, 497 million British pounds ($616 million) and $25.6 million respectively, the Justice Department said.

In setting the penalty, the Justice Department said it weighed the fact that Rolls-Royce did not come forward with the misconduct until media reports of the allegations began to surface. But U.S. authorities also showed Rolls-Royce leniency for later cooperating with authorities and fixing problems at the company.

(Additional reporting by Sarah Young and Kristin Ridley in London; Editing by Lisa Shumaker and Peter Cooney)

By Joel Schectman