Afghanistan's president said Thursday that 17 civilians were killed during clashes between US-led troops and insurgents. The American military insisted all 32 killed in the fighting were militants. Civilian deaths are a major source of friction between Afghan President Hamid Karzai and foreign troops here, and the latest claims threatened to worsen the tensions. The Western-backed president's shaky standing among Afghans has been further undermined by a string of reported civilian deaths in coalition operations. The killings have also damaged the reputation of foreign forces among ordinary citizens just as the troops are struggling to contain an increasingly virulent Taliban-led insurgency. In a statement, Karzai blamed the "terrorists" for using civilians as human shields in their battles with foreign troops, but also repeated a demand that coalition troops stop fighting in Afghan villages. The US military, however, said that all those killed in Tuesday's battle were militants involved with a bomb-making cell in eastern Laghman province.