In a statement, Karzai urged Pakistan to join Afghanistan in a joint campaign against terrorism, which he said threatened the citizens of both countries, Khaama Press reported Saturday.
The teenager, Aitzaz Hassan, died Monday after Pakistani police said he intercepted the bomber about 500 feet from the main gate of the school in a remote village in northwest Khyber Pakhtunkhwa province.
The bomber blew himself up at the school gates, wounding Hassan, who died later at a hospital. No one else was harmed.
Pakistani Prime Minister Nawaz Sharif has said President Mamnoon Hussain have been authorized to award Hassan the country's Sitara-e-Shujjat, or star of bravery. The teen also will receive the title of "shaheed," or martyred person.