Terming the killing of an American citizen in Pakistan's courtroom as a "shameful tragedy", the US State Department has called on Islamabad to take immediate action and institute reforms to prevent similar incidents in future.
Tahir Ahmad Naseem, from the minority Ahmadi community, was shot dead in a courtroom in Peshawar on Wednesday. He was on trial for blasphemy.
"Condolences to family of Tahir Naseem, an American citizen who was killed today inside a courtroom in Pakistan. We urge Pak to take immediate action and pursue reforms that will prevent such a shameful tragedy from happening again," tweeted Bureau of South & Central Asian Affairs, US State Department.
The young assailant, identified as Khalid Khan who managed to get into the court amid tight security was arrested later.
Naseem was arrested two years ago on blasphemy charges.
Ahmadis, a four million-strong minority group in Pakistan, have faced death, threats, intimidation and a sustained hate campaign for decades.
Pakistan's controversial blasphemy law carries an automatic death penalty for anyone convicted of insulting God, Islam, or other religious figures.
Many members of the minority communities in Pakistan - the Ahmadis, Hindus, Christians and Sikhs were charged with draconian blasphemy law. Many of them are languishing in jails on the false charges of disrespecting the Quran.
( With inputs from ANI )