Afghan policemen in Kabul, Afghanistan. Image Credit: Reuters

Kabul: A blast at a mosque on the outskirts of the Afghan capital during Friday prayers killed at least 12 people, police said, shattering the relative calm of a three-day ceasefire.

"During Friday congregation an explosion happened inside a mosque in Shakar Darah district of Kabul (province)," said Ferdaws Framurz, the spokesman for Kabul police.