The Friday morning attack near a shrine in Jhal Magsi District has lead to deaths of 18 people while as many as 22 people have also been injured.
In February this year at least 75 people were killed in an attack on Pakistan's Lal Shahbaz Qalandar shrine in the southern city of Sehwan in Sindh province.
He added that one police constable was killed while attempting to stop the suicide bomber from entering the shrine, while two other policemen were injured in the blast.
Provincial home minister Sarfaraz Bugti confirmed the toll.
Devotees gather at the shrine of the revered Sufi saint every Thursday to participate in a sufi dance called "dhamaal" and prayers. "The severely wounded are being moved to other facilities", district heath official Rukhsani Magsi said.
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No group has claimed responsibility for the suicide attack yet, but Pakistan's officials often blame extremist groups such as Baluchistan's separatist insurgent group for such terrorist acts.
The local administration declared an emergency at hospitals in Sibbi and Dera Murad Jamali.
The bomber detonated his explosives vest when he was stopped for a routine search by a police officer guarding the shrine in the village of Jhal Masgi, about 400 kilometers (240 miles) east of Quetta, the capital of Baluchistan province. Militants opposed to pluralist interpretations of Islam have targeted shrines such as this before.
"The suicide bomber struck outside the shrine at a time when it was packed with people, attending anniversary celebrations of Syed Cheesal Shah", Kakar said.