Monterrey casino attack: Mexican police officer held Published duration 2 September 2011

image caption Extra police and troops have stepped up security in the wake of the casino attack

A Mexican state police officer has been arrested in connection with the arson attack on a casino in the northern city of Monterrey that killed 52 people.

The Mexican Attorney General's office said the officer had been caught on CCTV pulling up in a vehicle outside the casino as the attack was launched.

Five men, suspected of belonging to the Zetas drug cartel, have been arrested.

Police are investigating whether the casino was attacked because protection money had not been paid.

Security in Monterrey has been boosted by the arrival of hundreds more police and troops since the attack just over a week ago.

Cartel infiltration

Jose Salinas of the Attorney General's office told reporters that the arrested Nuevo Leon state police officer was now in the custody of federal investigators.

The governor of Nuevo Leon state Rodrigo Medina said earlier this week that five people suspected of belonging to the Zetas cartel had confessed to being involved in the arson.

image caption The deaths in Monterrey shocked the entire country

He said at the time that two other people were being sought in connection with the blaze.

Several gunmen burst into Monterrey's Casino Royale in broad daylight, dousing it with fuel and setting it alight.

Panic ensued with people inside struggling to reach the emergency exits or taking refuge in back offices or toilets. Many were overcome by smoke which spread rapidly through the building.

The attack was one of the deadliest episodes of violence since President Felipe Calderon launched his crackdown on drug gangs in late 2006.

Monterrey and the state of Nuevo Leon have seen rising violence as the Zetas and Gulf cartels vie for control of trafficking routes to the US.

The drug gangs are also known to have infiltrated the local police. Nuevo Leon is in the process of recruiting new officers and retraining existing ones after firing much of its police force upon discovering the extent of the problem.

Some 40,000 people have been killed in drug-related violence across Mexico in the past five years.