KABUL: A well-known imam and a worshipper were killed in a prayer-time bombing at a popular mosque in Kabul's fortified Green Zone on Tuesday, officials said.

The latest attack in the Afghan capital came after seven civilians were killed in the north of the country in a roadside bomb blast authorities blamed on the Taliban.

No group immediately claimed the evening explosion in central Kabul, which occurred at one of the city's most famous places of worship. A loud blast sent shockwaves through the sprawling militarised zone, where alarms sounded at various embassies and international offices, sending staff rushing into safe rooms.

"Unfortunately, this evening some explosives placed by terrorists in Wazir Akbar Khan mosque detonated," interior ministry spokesman Tareq Arian told AFP.

The mosque's imam, Ayaz Niazi, was among those killed, Arian said.

President Ashraf Ghani's spokesman called the incident a "heinous" attack.