Police in northwestern Pakistan have launched a manhunt for suspects, including a Muslim professor, accused of killing a colleague from the minority Ahmadiyya sect following arguments on religion, officials said.

On Monday, two men in Peshawar city shot dead Naeemuddin Khattak, who held a doctorate in zoology and was a teacher at a college, police officer Ashoor Khan told the dpa news agency on Tuesday.

Khattak’s brother told police a Muslim professor from another college with whom the 56-year-old victim had heated arguments on religion shot him, Khan said.

“We are raiding possible hideouts to arrest the suspect,” the police officer said.

The incident occurred two months after a Pakistani-American man who belonged to the Ahmadiyya sect was shot dead inside a court during his trial under Pakistan’s blasphemy law.

The US State Department criticised the killing, urging Pakistan to repeal such laws to prevent crimes triggered by religious hatred.

Pakistan’s four million-strong Ahmadiyya group has faced death, intimidation and a sustained hate campaign for decades.

Ahmadis insist they follow Islam. However, Pakistan declared the group non-Muslim in 1974 for regarding their sect’s founder, Ghulam Ahmad, as a prophet. Orthodox Islam holds Muhammad was its last prophet.

More than 260 members of the sect have been killed in gun or bomb attacks since 1984 when the sectarian violence started in Pakistan, according to statistics compiled by the community.