The Nigerian authorities say more than 150 inmates have escaped from a prison, which partly collapsed during heavy rain.
The medium-security jail is near the central city of Lokoja in Kogi state, where two rivers meet.
The area is prone to flooding and there are reports that several houses have been submerged.
Correspondents say Nigeria’s prison system is congested and poorly maintained.
In June last year, more than a 180 prisoners escaped from the same facility following an armed attack blamed on criminal gangs trying to free their associates.