Suicide bomber kills 20 at Afghanistan's top court

A suicide bomber on foot ripped through a crowd of Afghan Supreme Court employees on Tuesday, killing at least 20 people and wounding 41 others in the second attack on government institutions in under a month.

The assailant detonated the device in the car park as employees were boarding a bus to go home. The bomber appeared to have entered an area where guards were performing security checks when he detonated the explosives.

According to Najib Danish, a spokesman for the interior ministry, the suicide bomber entered on foot.

"Twenty people were killed (including 3 women & one child), and 41 others were injured in today's suicide attack in Kabul," health ministry official Wahidullah Mayar wrote on Twitter.

The ministry warned the toll could rise still further.

There was no immediate claim of responsibility for the attack.

The shook nearby buildings, smashing windows and blasting debris onto the streets.

Police have blocked off the road around the high-profile compound located near the US embassy.

President Ashraf Ghani condemned the attack in a statement, calling it a "crime against humanity and an unforgivable act".

The Taliban have previously targeted the Supreme Court. They killed 15 civilians with a suicide car bomb at the entrance to the compound in 2013.

At the time the insurgent group threatened further attacks on the judiciary if it continued to sentence its militants to death.

Last month twin suicide blasts claimed by Taliban fighters tore through employees exiting a parliament annex in Kabul, killing 30 people and wounding 80.