At least four people, including two bomb disposal experts, were killed on Tuesday in an explosion at a cement factory in southern Pakistan, police said.

According to the Deutsch Presse-Agentur, dpa, a large store of explosive material, used to break down large stones for use in the cement-making process, was apparently ignited accidentally at the Rohri Cement Factory in southern Pakistan's Sindh province.

A member of the paramilitary rangers and a factory worker were also killed in the blast, police spokesman Mir Bilal Ahmed said.

Four people including a factory manager were injured and taken to hospital.

The explosives had been found by paramilitary forces during a sweep of the premises.