The police officers were providing an escort to gold mine workers, said AFP.

A similar attack killed five officers in the area in August. 

Media reports suggest the situation is worsening, with militant attacks spreading from initially isolated incidents in the north, more recently to the east near the border with Togo and Benin.

AFP also reported that six people were shot dead on Monday by police forces.

Montreal-based Semafo said the incident Friday did not affect operations at the Boungou mine, more than 40km away, and no Semafo employees were involved. Senior management continued its discussions with the government regarding the security of the public road, the company said.

"We remain strongly committed to ensuring the highest levels of safety and security for our employees and operations. The corporation would like to express its sincere sympathy to families of the victims in addition to its firm support of Burkina Faso's security forces," the company said.

Semafo had sharpened its security protocols after both its Burkina Faso mines were involved in armed attacks in recent months. 

Semafo shares fell by C17c in early trading to reach a new one-year low of $2.23, before eking out a gain of 1.25% or 3c in the afternoon session to finish at $2.43, which gives the company a value of $791.3 million.