The ministry described the four as “terrorists”.

It did not identify the escapees or say why they were in prison.

It, however, said an exchange of gunfire followed their late Sunday breakout, and two national guard members were killed and two were wounded.

The national guard had secured the prison and was in pursuit of the four, the ministry said.

The arid West African country has been spared the kind of violence unleashed by Islamist groups linked to al Qaeda and Islamic State that has killed thousands in nearby countries in the Sahel region.

Mauritania has not recorded an attack in years, but it shares a long border with Mali, where armed groups are active. (www.amatropics.com)