Authorities in Niger on Monday foiled a "terrorist" attack on a high-security prison near the capital Niamey, Interior Minister Mohamed Bazoum said.
"Around 10 armed assailants tried to attack the prison at around 16:00 GMT but were repelled because the security forces were already aware of an impending raid," a security source told AFP.
"There are no deaths in our ranks for the moment," Bazoum said.
The Koutoukale prison, some 50km north of Niamey, holds many jihadists.
The security source said the assailants infiltrated the Koutoukale market to launch their attempt on the prison.
The prison was previously attacked in October 2016 by assailants aboard motorbikes wielding explosives.
Considered to be Niger's most secure prison, the facility holds the country's most dangerous detainees, including jihadists from groups active in the Sahel area and Islamist militants from Nigeria's Boko Haram.
It also holds security prisoners from neighbouring Mali.
Niger, along with Chad and Cameroon, suffers from the spillover of Boko Haram's decade-long uprising to establish a hardline Islamic state in Nigeria's northeast.
The conflict has killed more than 27 000 people and left 1.8 million homeless.