At least 31 inmates were killed and 13 others wounded Wednesday in a prison gang-fight in Altamira, a town in the northern state of Tamaulipas, officials said.
State government spokesman Guillermo Martinez confirmed the 31 deaths to local press, of which 22 were serving sentences for state crimes and nine for federal offenses. He said the riot which involved knives and homemade guns, broke out in the afternoon and was controlled hours later, Xinhua reported.
Public Security Ministry said in a statement that the fight erupted around 17:00 local time (2300 GMT) when inmates of module 11 entered the module 12 at the prison of Santa Amalia which jailed more than 3,000inamtes despite its holding capacity of 2,000.
State authorities responded immediately to put the situation under control and successfully restored order with the intervention of security forces, it said.
Authorities have arrested 13 suspects while further investigation will continue Thursday.
The prison is located in a port area guarded by military and federal police. The riot is the most serious of its kind in the country over the past 12 months.
The prisons of Tamaulipas, home to some 7,800 prisoners and most of whom are convicts of drug crimes, have witnessed a number of jailbreaks and gang-fights in recent years.
On Oct. 15, a riot erupted in a prison in the city of Matamoros, leaving 20 dead and 12 others wounded.
Tamaulipas, an epicenter of gang activities of Los Zetas and the Gulf drug cartels, is regarded as one of the most violent regions of Mexico. At present both gangs are fighting a bloody battle for the control of drug routes as their members account for a large portion of the state's prison population.
More than 45,000 people have been killed in drug-related violence in Mexico since President Felipe Calderon launched the "war against organized crimes" in 2006.