A total of 85 inmates escaped a prison in the Mexican town of Reynosa near the U.S. border, Mexico's El Universal newspaper reported.
The paper gives no further details of the break from the prison, in which many drug cartel members are being kept, RIA Novosti reported.
A total of 44 prison employees face criminal investigation in connection with the jailbreak.
Crime is among the most urgent concerns facing Mexico, with drag trafficking being the country's major woe.