The mastermind of the Peshawar blast along with one of his companions was on Saturday killed in a targeted operation in the suburb of the district, which lies at the heart of Pakistan's restive Khyber Pakhtunkhwa province, police said.

According to the police, the terrorist named Hassan Shah, a resident of district Khyber, was killed in Pishtakharra of Peshawar in a joint counter-insurgency operation conducted by Peshawar police and the Counter-Terrorism Department of Pakistan.

The slain terrorist was gunned down along with his companion, the police confirmed.

According to the police, both the terrorists belonged to a banned outfit of the Tehreek-e-Taliban Pakistan (TTP), a militant organisation fighting the government of Pakistan to enforce the law of Sharia across the South Asian nation.

The police said the security forces had geared up the search operation in the area to arrest the remaining culprits.

As many as 57 people were killed and over 200 injured in the suicide blast at the Ahle Tashih mosque of Kucha Risaldar in Peshawar city on March 4 this year.

The militant group Islamic State, claiming the responsibility for the attack, had added that the lone suicide bomber was from neighbouring Afghanistan.

The attack in Peshawar's congested old city was the worst in years in Pakistan as the country faces renewed militant attacks mostly carried out by the Pakistani Taliban since last August when the Afghan Taliban swept into power and America ended its 20-year involvement in Afghanistan.