By Patrick Markey BOGOTA, Dec 22 (Reuters) - Colombia pushed on with chemical spraying of the plant used to make cocaine along its border with Ecuador on Friday, stoking more diplomatic tensions between the Andean neighbors. Ecuadorean President-elect Rafael Correa on Thursday canceled a planned trip to Bogota in protest against the fumigation with the herbicide glyphosate, which Quito says is damaging crops and harming residents. Colombia, a key ally to Washington in the region that gets millions of dollars in U.S. military aid to fight the cocaine trade and left-wing rebels, insists the spraying is safe and essential to destroy new coca leaf crops in the border area. "Up until now we have sprayed about 50 percent of the fields where there are crops and in about five or six days we should be finished with the fumigation," Interior Minister Carlos Holguin told local radio. Ecuador -- saying the herbicide carries risks of skin burns, genetic damage and skeletal retardation -- has already recalled its ambassador from Bogota for consultations and wants to see studies to prove the chemical is safe. Speaking in Peru, Ecuador's Foreign Minister Francisco Carrion said Quito was preparing documents to present a case against Colombia in the Inter-American Court of Human Rights. Last year, Colombia stopped spraying glyphosate after Ecuador complained and asked the United States to research possible health threats. But President Alvaro Uribe ordered the spraying resumed this month after new coca crops were found. "Since December last year, we opened communication to bring relations to the level they were years ago. But the fumigation put all that work at risk," Ecuador's Deputy Foreign Minister Diego Ribadeneira told reporters. Colombia refers to a study by the Washington-based Organization of American States showing the chemical does not harm crops, humans or the environment. Colombia also notes Ecuador used the same substance in its agriculture sector. Correa joined Venezuela's President Hugo Chavez in attacking Colombia's Washington-backed program to eradicate the coca crop, which helps fuel its rebel conflict. Colombia produces around 600 tonnes of cocaine a year, most of it smuggled into the United States and Europe. Marxist guerrillas and right-wing paramilitary outlaws fighting in Colombia's four-decade conflict have reaped millions of dollars from the cocaine and heroin trade. (Additional reporting by Alexandra Valencia in Quito and Maria Luisa Palomino in Lima)
