Kabul: The death toll rose to 20 on Tuesday from a bomb blast outside the Supreme Court in the Afghan capital of Kabul, the Ministry of Public Health said.

At least 48 injured people were taken to hospital after an apparent suicide bomber targeted Supreme Court employees leaving their offices at the end of the working day, police said.

Reuters witnesses had reported blood stains on the street and numerous ambulances leaving the area. There was no immediate claim of responsibility.

A suicide bomber on foot detonated as employees were boarding a bus to go home in the parking lot of the court compound, located on the road leading from the international airport to the US embassy, interior ministry spokesman Najibullah Danish told AFP.

The casualty figures came from health ministry spokesman Waheed Majroh, who added that women and children were among the wounded.

Police had blocked off the road around the compound as panicked relatives of court employees began to gather, and ambulances and fire trucks arrived on the scene.

The blast comes after twin Taliban explosions tore through employees exiting a parliament annexe in Kabul last month, killing at least 30 people and wounding 80 others.

The carnage underscores growing insecurity in Afghanistan, where US-backed forces are struggling to combat a resilient Taliban insurgency as well as Al-Qaeda and Islamic State militants.