General David Petraeus, recently-appointed US and NATO commander in Afghanistan, has issued a new guideline for foreign troops stressing the need to protect civilians during anti-Taliban operations, the military said Wednesday. The commander of 140,000 US and NATO troops, who took the command on July 4, mainly reversed the existing directive issued by his predecessor, General Stanley McChrystal, dpa quoted the alliance as saying in a statement. The new directive, however, re-emphasizes the need to avoid civilian casualties and clarifies some of the rules, including military commanders' freedom to use lethal force in populated areas when the safety of NATO or Afghan forces is at risk, it said. "We must continue - indeed redouble - our efforts to reduce the loss of innocent civilian life to an absolute minimum. Every Afghan civilian death diminishes our cause," Petraeus said in a statement issued by his headquarters in Kabul. "Our enemies will do all that they can to shake our confidence and the confidence of the Afghan people," he said, adding, "In turn, we must continue to demonstrate our resolve to the enemy. We will do so through our relentless pursuit of the Taliban and others who mean Afghanistan harm." The directive was released around an hour after the Afghan government said its investigating team found that a NATO rocket in southern province of Helmand killed 39 civilians, including women and children, and injured four others on July 23. The investigating team, including Afghan members of parliament and provincial officials reported their finding to President Hamid Karzai on Wednesday, the presidential palace said in a statement. The team found that on that day the civilians had gathered in one compound, from where the Taliban militants had fired on the Afghan and coalition forces, the statement said, adding that NATO's return fire hit the house, causing the civilians deaths. Civilian casualties at the hands of international forces have always been a main source tension between the Afghan government and foreign troops. Such grievances were addressed by McChrystal in 2009 when he announced his new guideline, which limited the use of airstrikes in populated areas. The new Petraeus's directive also warns the allied forces that "If we use excessive force or operate contrary to our counter-insurgency principles, tactical victories may prove to be strategic setbacks".