More than 50 people were killed and dozens more wounded in Pakistan's Balochistan province on Friday by a suicide bomber targeting a procession marking the birthday of Islam's Prophet Mohammed, officials said.

A second suicide attack by two men at a mosque hundreds of kilometres north in Khyber Pakhtunkhwa province led to a roof collapse that killed four people, officials said.

While the celebration of the Prophet's birthday is accepted by the majority of Islamic sects in Pakistan and elsewhere in the Muslim world, certain denominations view it as an unwarranted innovation.

In southwestern Balochistan, officials said a suicide bomber detonated a device as rallies from neighbourhood mosques converged on a meeting point in Mastung, around 40 kilometres south of the provincial capital, Quetta.

"My feet trembled and I was thrown to the ground," said 49-year-old Hazoor Bakhsh.

"As the dust settled, I saw people scattered in all directions, some screaming while others called out for help."

Local hospitals were overwhelmed by the number of wounded, and provincial authorities used social media platforms to appeal for blood donors.

The death toll kept climbing throughout the day.

"I can confirm that the death toll has increased to 52, with over 70 individuals injured," said Munir Ahmed Shaikh, the deputy inspector-general of Balochistan's police force. (AFP)