Gunmen stormed a mosque attended by Shia Muslims in Kabul on 25 August and two suicide bombers set off an explosion that killed at least 20 people, including the cleric leading Friday prayers.

Around 50 people were seriously wounded in the attack at the Shia Imam Zaman Mosque. Isis claimed responsibility for the attack on its affiliated news agency Aamaq.

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Two of the attackers were suicide bombers. The other two were shot dead by police three hours after they launched the assault.

There were reports of explosions and gunfire. Witnesses said the gunmen threw grenades before entering the building.

"At first a suicide bomber opened fire and martyred two security guards at the entrance of the mosque and then they entered inside," eyewitness Sayed Pacha told Reuters. "Some people escaped out of the mosque including women, but there were four attackers who managed to enter the mosque."

A spokesman for the minister of interior said there were numerous casualties, but did not provide an exact number.

Earlier this month, Isis suicide bombers targeted a Shia mosque in the western city of Herat, killing at least 37 people and injuring 66.

It is the sixth time this year a Shiite place of worship in Afghanistan has been attacked.

Areas inhabited by Shia Muslims have repeatedly been hit by terror attacks in the past year, carried out by Isis and the Taliban.

Kabul suicide bombing
An Afghan boy mourns at the site of a suicide attack followed by a clash between Afghan forces and insurgents after an attack on a Shi'ite Muslim mosque in Kabul, Afghanistan, on 25 August 2017 REUTERS/Mohammad Ismail
Kabul suicide bombing
A woman and a child run after being rescued from the site of a suicide attack followed by a clash between Afghan forces and insurgents after an attack on a Shi'ite Muslim mosque in Kabul, Afghanistan, on 25 August 2017 REUTERS/Mohammad Ismail
Isis