WASHINGTON: Drawing upon their success in strikes against al Qaeda and Taliban, the US has started sending drones deep into the Mexican territories to locate and pinpoint drug lords. The Pentagon began flying high-altitude, unarmed drones over Mexican skies last month as the fight between security forces and drug gangs have left thousands dead in an almost year-long war. The US security would turn over the intelligence data to Mexican law enforcement agencies, American military officials were quoted as saying by the New York Times. The paper said US President Barack Obama and his Mexican counterpart, Felipe CalderÃ³n, formally agreed to the surveillance flights during a White House meeting on March 3, but have kept it secret because of legal restrictions in Mexico and the heated political sensitivities there about sovereignty. The Pentagon has flown a number of flights over the past month using the Global Hawk drones -- a spy plane that can fly higher than 60,000 feet and survey about 40,000 square miles of territory in a day. They cannot be readily seen by drug traffickers -- or ordinary Mexicans -- on the ground. The drones gathered vital information leading to Mexico's arrest of several suspects in last month's killing of US immigration and customs agent Jaime Zapata. Mexican and US officials said that their joint efforts had led to the capture or killing of at least 20 high-level drug traffickers, including 12 in the last year alone, the NYT reported. In addition to expanding the use of drones, the two leaders have agreed to open a counter-narcotics "fusion" centre, the second such facility in Mexico, where Mexican and American agencies would work together, the officials said.