For years Colombian security forces systematically killed civilians and presented the bodies as casualties of war to boost the military’s image in the fight against guerrilla groups, according to a new report released Wednesday by international watchdog organization Human Rights Watch. The murders were carried out by soldiers under pressure from their superiors to produce “positive” results in the military’s ongoing war against rebel insurgencies, a conflict that dates back decades.

News of the military’s civilian murders came to light in 2008, but Human Rights Watch has found that the practice was far more widespread and that knowledge of it reached much further up the chain of command than was previously thought. The killings took place between 2002 and 2008, according to the group.

“False positive killings amount to one of the worst episodes of mass atrocity in the Western Hemisphere in recent years, and there is mounting evidence that many senior army officers bear responsibility,” José Miguel Vivanco, executive director, Americas Division, at Human Rights Watch, said in a statement. “Yet the army officials in charge at the time of the killings have escaped justice and even ascended to the top of the military command, including the current heads of the army and armed forces.”

Among the report’s most egregious finds was that about 3,000 civilians were killed by soldiers and passed off as combatants for over half a decade to pad body counts. Among the victims were young men and teenage boys from the suburbs of Bogotá, the nation's capital. In some instances, soldiers were given extra vacation days as a reward for producing more dead bodies.

In many cases, the civilians were tricked into showing up at remote locations, usually under false pretenses such as the promise of work, and then murdered. Weapons were placed by their bodies to give the appearance that they were rebel combatants. Their deaths were reported as guerrilla fighters. Human Rights Watch identified more than 180 battalions and units that carried out the killings. Authorities have convicted more than 800 soldiers in the civilian murders.

The Colombian government has fought a decadeslong war against leftist insurgencies -- the Revolutionary Armed Forces of Colombia and the National Liberation Army. The internal war has resulted in tens of thousands of deaths over the past 60 years. Millions of others have been displaced because of the conflict, according to The war has often involved political killings, kidnappings and widespread use of land mines and other explosive devices.