Ten young girls were killed when a landmine exploded while they were collecting firewood in eastern Afghanistan's Nangarhar province on Monday, officials said.The girls, aged between nine and 11, died when one of them accidentally struck the mine with an axe, Chaparhar district governor Mohammad Sediq Dawlatzai told AFP."An old mine left over from the time of the jihad (against Soviet troops in the 1980s) exploded, killing 10 girls and wounding two others," he said.Nangarhar provincial government spokesman Ahmad Zia Abdulzai said, however, that the mine was planted by "the enemies of Afghanistan" -- a reference to Afghan Taliban -- even if it had been in that spot for some time.The girls were collecting firewood early in the morning before heading for school in the Taliban-troubled district, Dawlatzai said.Most of the bodies were so badly shattered that they could hardly be recognised, he said.Since 1989, when the Soviets withdrew after a 10-year military occupation, nearly 700,000 mines and more than 15 million other explosive left-overs from decades of war have been destroyed, according to UN figures.But despite international clearance efforts, more than three decades of war have left Afghanistan one of the most heavily-mined countries in the world.The explosives were placed during three recent conflicts: the 1980s war against the Russians, the 1990s civil war, and during fighting between the Northern Alliance and the Taliban before they were ousted from power in 2001.The Taliban now plant bombs, or improvised explosive devices, to target Afghan troops and their NATO backers but these regularly kill civilians.The militants use as bombs artillery shells, explosives in containers such as pressure cookers and devices made from the common fertiliser, ammonium nitrate.In the first six months of 2012, 1,145 Afghan civilians were killed and around 2,000 wounded, mostly by roadside bombs.There are more than a dozen organisations and contractors and around 13,000 deminers working to eliminate forgotten mines in Afghanistan."The mines and IEDs still hit between 20 and 30 people daily in different parts of the country," said Shah Wali Ayubi, operations manager at Kabul's Mine Detection Centre."There are still a lot of insecure areas where our teams cannot go... we only clear the abandoned IEDs in some parts of the country. We can only have access to those areas after the fighting ends there," he said.