The order is worth about $4.5 billion (3.1 billion EUR) at the plane's list price, though buyers typically negotiate steep discounts.
Santiago-based LAN Airlines also plans to lease six additional 787s from International Lease Finance Corp. The airline will also acquire four Boeing 777 freighters - two from Boeing and two on lease from General Electric's aviation division.
Boeing said last month it would delay the launch of its highly anticipated Dreamliner by six months to November or December 2008 because of assembly problems.
Russia has left the list of 33 largest holders of US government bonds, after the country disposed of at least a third of remaining bonds