The Mexican Interior Department is to investigate whether there were illegal games in operation at Casino Royale in Monterrey, where an arson attack killed 52 people in August.

Several suspects - including a police officer - have been arrested in connection with the August 25 blaze. Now, the authorities are hoping to determine whether the casino, which had permits to operate certain gambling activities, was also running games that it was not authorised to do so, such as roulette and card games.

Until a few years ago, Monterrey was among Mexico’s safest cities but recent drug-related violence and organised crime have seen a dramatic increase in murders. Some reports suggest that owners of casinos have been targeted by criminal gangs for refusing to meet their demands for protection money.