Australia's Fortescue reaches $715 mln debt deal with Leucadia SYDNEY (Reuters) - Australia's Fortescue Metals Group (FMG.AX) has reached a $715 million deal with U.S. investment firm Leucadia National Corp (LUK.N) to repay a loan, the latest move by the world's No.4 iron ore producer to restructure its $11.7 billion debt load. Hammered by a slump in iron ore prices, Fortescue earlier this week lined up $4.5 billion to restructure part of its debt and said it was in talks to sell stakes in some of its assets. Leucadia purchased $100 million of unsecured notes in 2006. The notes were to pay Leucadia 4 percent of the revenue from two of Fortescue's mines until maturity in August 2019 and were valued in Fortescue's book at $897 million, Fortescue said. "This agreement significantly reduces the overall cost of debt for the company," Fortescue CEO Nev Power said in a statement on Thursday. Leucadia was one of the first big backers of Fortescue -- one-third owned by billionaire founder Andrew "Twiggy" Forrest -- as it embarked on an ambitious plan to build a series of new mines, a railway and port facilities to take on iron ore giants BHP Billiton (BHP.AX) and Rio Tinto (RIO.AX) in Western Australia's Pilbara district. But Leucadia sued Fortescue and Forrest in 2010, saying it needed to protect the $100 million subordinated note from potential dilution. Leucadia said the deal on Thursday would settle all legal action without any further payment. Leucadia sold its equity stake in Fortescue between 2011 and July 2012, reaping a profit of more than $1 billion on its $444 million investment. Shares in Fortescue were little changed at A$3.68 on Thursday, having rallied from a three-year low of A$2.81 earlier this month. The stock had been hammered after the company unexpectedly wound back expansion plans and slashed spending just days after reassuring investors on its plans and prospects. News it was seeking some relief from lenders about banking covenants further weighed on the stock. Including bonds, notes and undrawn facilities, Fortescue's total debt before this latest deal was about $11.7 billion, mostly in unsecured U.S. "junk" bonds. The company's credit rating remains under review from all three main ratings agencies. Reporting by Lincoln Feast; Editing by John Mair and Edwina Gibbs