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 Taliban insurgents - even if it had been in that spot for some time.
Since 1989, when the Soviets withdrew after a 10-year military presence, nearly 700,000 mines and more than 15 million 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 was ousted from power in 2001.The Taliban now plant bombs, or improvised explosive devices, to target Afghan troops and their NATO backers but which regularly kill civilians.