The Ministry statement did not say how many prisoners had escaped Koutoukale, which lies 50 kilometres northwest of the capital, Niamey, or how they had done so.

In 2016 and 2019, attempted jail breaks at the facility were repelled.

The prison's inmates include detainees from the West African country's conflict with armed groups linked to al Qaeda and Islamic State and suspected Boko Haram insurgents.

Local authorities imposed an overnight curfew in the urban commune of Tillaberi, which is in the same region as the prison, but did not give further details.

Niger and its neighbours in the central Sahel region are on the frontlines of the battle to contain a jihadist threat that has steadily grown since 2012, when al Qaeda-linked fighters first seized parts of Mali.

Thousands have been killed in the insurgencies and more than 3 million displaced, fuelling a deep humanitarian crisis in some of the world's poorest countries.

--Reuters--