The miners were sleeping in a makeshift camp near a coalfield in Harnai district, about 167 km from provincial capital Quetta, when a group of armed men took them away at gunpoint.
Official Sajjad Gul Kakar told The Express Tribune newspaper that initial investigation suggested a Baloch separatist group had kidnapped the miners.
No group claimed responsibility for the kidnappings.
"The coalminers belonged to Khyber-Pakhtunkwa and a manhunt has been initiated in the area," another official said.
He said Baloch separatist groups often kidnap miners to stop mining companies from extracting coal and other natural resources.
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Militants kidnapped seven coal miners from Quetta district's Degari area on July 7 last year and their bodies were later found in the area.
Dawn reported that Shahrag has rich coal reserves and thousands of miners have been working in deep coal mines. Most of the miners come from Khyber-Pakhtunkhwa and Afghanistan's volatile southern region.
Several nationalist groups are active in Balochistan, with their demands ranging from more autonomy to complete independence. They allege the federal government is robbing the province of its vast natural resources.