A powerful blast killed more than 50 worshipers after Friday prayers at a mosque in Kabul, its leader said, the latest in a series of attacks on civilian targets in Afghanistan during the holy month of Ramadan.

According to foreign media, the Telegraph reports, the blast hit the Khalifa Sahib Mosque west of the capital in the early afternoon, said Besmullah Habib, deputy spokesman for the Foreign Ministry, who said the official confirmed death toll was 10.

The attack came as worshipers at a Sunni mosque rallied after Friday prayers for a congregation known as Zikr - an act of religious remembrance practiced by some Muslims but seen as heretical by some hardline Sunni groups.

Sayed Fazil Agha, the head of the mosque, said someone they believed was a suicide bomber joined them at the ceremony and detonated explosives.

"Black smoke rose and spread everywhere, corpses were everywhere," he told Reuters, adding that his grandchildren were among the dead.

"I survived, but I lost my loved ones."