LONDON, May 26 - In a plan that will eventually link sites around South America to sites in the Caribbean and the US via a broadband fiber-optic network, three telecommunications companies from different continents announced the creation of Southern Cone Communications Co. Collaborating on the $220-million (US) project are UK-based electric and telecom utility National Grid Group; Chilean carrier Telefonica Manquehue; and Williams Communications, a US-based global provider of services to the carrier market.Initially Southern Cone will link between major cities in Argentina and Chile. Eventually Cone's 48 fibers will be available to other carriers in the form of dark fiber or dedicated capacity. The end-points of the 2,660-mile cable will connect to the landing points of international submarine cables that are hoped to encompass all of South America. Upon completion the system will link to cables in Colombia, Panama, Venezuela, Brazil and the Caribbean, and ultimately to Williams' network in the US. National Grid will represent 50 percent of the company with its investment of $61 million (US). Williams' $24.5-million investment represents a 19.9 percent stake while Telefonica Manquehue will own a 30.1 percent share with its $37-million investment. National Grid announced that it will also invest $80 million in Telefonica Manquehue in return for a 30 percent interest in the Chilean carrier. Williams Communications already owns 16.4 percent of Manquehue.