Human Rights Watch is urging Pakistan to act to protect Shi'ite Muslims and not stand by as members of the country's religious minority are “slaughtered.”

In one of the deadliest attacks, gunmen last month killed 22 Shi'ites after ordering them off buses in the southwestern province of Baluchistan. Just last week, eight Shi'ite members of the ethnic Hazara community were killed in two attacks in the provincial capital, Quetta.

Human Rights Watch Asia Director Brad Adams said Wednesday the Pakistani government's “persistent failure to apprehend attackers or prosecute the extremist groups organizing the attacks suggests that it is indifferent to this carnage.”

The New York-based rights group says 320 Shi'ites have been killed in targeted attacks this year, many in Baluchistan, the southern port city of Karachi, the northern Gilgit Baltistan area and the northwestern tribal region.

Human Rights Watch says banned Sunni militant groups such as Lashkar-e-Jhangvi often operate with widespread impunity across Pakistan, with some Sunni extremist groups allied with the Pakistani military and intelligence agencies.

Last week, Pakistani police said they arrested the founder of Lashkar-e-Jhangvi for making a speech aimed at stirring sectarian hatred. Human Rights Watch called Malik Ishaq's detention an important development and an important test for Pakistan's criminal justice system.