KANDAHAR, Afghanistan, April 1 (Reuters) - Taliban guerrillas hanged three Afghans on Sunday, accusing them of spying for NATO's British troops in Afghanistan, a rebel commander and villagers said. The three were hanged from trees in front of villagers in the town of Musa Qala in southern Helmand province, part of the Taliban stronghold and the main drug-producing region of Afghanistan, the world's leading producer of heroin. "They were spying for the British troops and had tipped them off about the location of one of our commanders who was killed by an air strike," Nizamuddin, a provincial Taliban commander, told Reuters by phone from the district. Villagers said they saw three strangled bodies in the town. Ousted from power in 2001, the Taliban have declared a holy war against Western troops or any one backing them or the government of President Hamid Karzai. Separately, Taliban Islamists killed seven policemen in an ambush late on Saturday in neighbouring Kandahar province, provincial police there said. The incident is part of rising violence by militants ahead of an expected spring offensive following the bloodiest year in 2006 since the Islamists were driven from power.