Kabul: The notorious Organization Islamic State has come forward to claim responsibility of the yesterday’s suicide attack outside Afghanistan Supreme Court at Kabul resulting in at least 22 casualties.

The bomber, identified as Abu Bakr Altajiki by the militant group, detonated an explosive belt as court employees were leaving work in downtown Kabul on Tuesday evening.

"The apostates must know, starting with the tyrant judges, that their blasphemous judgments will not pass without severe punishment," the Islamic State statement said.

White House spokesman Sean Spicer called the blast a "cowardly attack" and said U.S. national security adviser Michael Flynn had phoned his Afghan counterpart, Mohammad Atmar, to "reaffirm our support to the Afghan government".