BROOMFIELD, Colo., Aug. 25 -- Level 3 Communications Inc., a global communications and information services company with metropolitan networks in 56 US and 21 international markets, has signed a letter of intent to buy more than two million cabled fiber kilometers of Corning Inc.'s new LEAF optical fiber. The fiber will increase the capacity and cost efficiency of Level 3's inter-city networks in the US, the company said. Level 3 will be the first to install Corning's new optical fiber, which is designed to handle emerging high-speed, long-reach transport systems. Level 3 will begin deployment of the fiber in the second conduit of the network during the first quarter of the next fiscal year and be mostly finished by the end of the year, the company said. Corning Cable Systems, a wholly owned Corning subsidiary, will continue to provide the cable for all of the LEAF fiber required for this next stage of network development.