The Express Tribune reported the banned militant group Lashkar-e-Jhangvi allegedly has targeted the Shiite and Hazara communities throughout Balochistan.
The newspaper said a decade-long insurgency has become a battleground for politically motivated attacks on religious sects.
The provincial home department report said more than 400 Shiites and Hazaras had been killed in more than 200 incidents in the four-year span through 2011 and about 100 pilgrims had been killed in the first half of this year.
From 2008 to 2011, 450 people also were injured in more than 110 sectarian attacks.
The violence has been on the increase. Last year, more than 120 Shiites and Hazaras were fatally shot, and nearly 100 suffered injuries.
Police have arrested alleged terrorist Sher Dil, also known as Babu, who reportedly had links with Lashkar-e-Jhangvi. But suspects including Usman Saifullah and Ziaul Haq have not been caught.