By Taos Turner BUENOS AIRES--Claro, a unit of Mexico's America Movil SAB (AMX, AMX.MX), plans to invest $249 million in Argentina in the remainder of 2012 to build new cell sites and extend fiber-optic connections around the country. The investment, which is in addition to a previously revealed $1 billion investment program for 2011-2012, will allow the company to build 150 more cell sites than originally planned, raising the number of sites to be built in the rest of the year to 450, Claro said in a statement Thursday. The company is moving quickly to raise the total number of its cell sites connected by fiber-optic cable to more than 1,400. Cell sites refer to where antennas and other communications equipment are housed to support cellular networks. Claro is the largest of Argentina's four mobile companies with almost 20 million customers. Telecom Argentina SA (TEO, TECO2.BA) reported 18.2 million wireless subscribers at the end of 2011, followed by Spain's Telefonica SA (TEF, TEF.MC) with 16.7 million and the Nextel Argentina unit of U.S.-based NII Holdings Inc. (NIHD) with 1.5 million. Claro said it also has increased the size of its data center and finished extending a $15 million, 510-kilometer fiber-optic cable linking the island of Tierra del Fuego to nearby communities in Argentina and Chile. Meanwhile, the company said it will continue extending its urban fiber-optic network, which aims to offer household broadband access. In November, Claro said it became the first company in Argentina to launch a 4G service, offering download speeds of up to five megabits per second. That surpasses the average home broadband speed using cable modem or ADSL. In its statement Thursday, the company said it is "optimistic" about government plans to auction 850 megahertz and 1900 megahertz spectrum, though it's unclear when the auction may take place. Argentina boasts one of the highest mobile-phone-ownership rates in the world, thanks in part to Argentines' adoration of technological gadgets. In 2010, Argentina had about 142 mobile phones for every 100 residents, according to the International Telecommunications Union. By comparison, Brazil had 104 per 100 residents, Japan 95 and the U.S. 90. Write to Taos Turner at email@example.com.