In a message to Afghanistan President Mohammad Ashraf Ghani, Mukherjee said India strongly condemned the "cowardly act" and stood "in solidarity" with the Afghan people.
"This is yet another instance of senseless violence that cannot be justified under any circumstances," he said.
President Mukherjee extended to Ghani the "heartfelt condolences" of the government and people of India and wishes for a "full and speedy recovery" of those injured in the attack.
A truck bomb ripped through Kabul's diplomatic area today, killing 80 people and wounding hundreds.
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