Mexican federal police have arrested the mayor of the resort city of Cancun on drug trafficking, money laundering and organized crime charges, the latest blow to 2010 state and local elections already marred by violence and allegations of drug cartel involvement.

Gregorio Sanchez, who took a leave of absence from the Cancun mayoral post to run for governor of the Caribbean coastal state of Quintana Roo, was taken into custody Tuesday at Cancun's international airport after arriving on a flight from Mexico City.

The federal Attorney General's Office said Sanchez is suspected of offering information and protection to the Zetas drug gang and the Beltran Leyva cartel, which are active in Quintana Roo.

Officials said they could not immediately recall another case in which a gubernatorial candidate had been arrested on drug charges.

"This takes us all by surprise, it is unprecedented," said current Quintana Roo Gov. Felix Gonzalez Cantu.

Ricardo Najera, a spokesman for the federal Attorney General's Office, said the charges allege Sanchez played a role in fomenting or aiding drug trafficking, engaging in organized crime and making transactions with illicitly obtained funds.

Sanchez's website carried an article in which the candidate for the leftist Democratic Revolution Party and two smaller parties said he was being persecuted for political reasons. The site quoted Sanchez as saying he had been threatened.

"Resign from the race, or we are going to put you in jail or kill you," Sanchez said in describing one of the threats.

Bitter political fight

Sanchez, a populist who pledged to bring services to the impoverished majority of residents who live on the outskirts of the glittering resort, took on the established and entrenched political machine of the long-ruling Institutional Revolutionary Party.

The political fight in the state has been bitter — soldiers discovered two apartments fitted out with equipment for telephone eavesdropping that local media said may be linked to political espionage.

But drug cartels have long been active in the state, as well. In 2009, prosecutors arrested Cancun's police chief, Francisco Velasco, to investigate whether he protected the Zetas drug gang.

Velasco already was detained for questioning in the killing of retired Brig.-Gen. Mauro Enrique Tello, whose bullet-riddled body was found in a car in early 2009, shortly after the Cancun city government hired him as a security consultant to combat local corruption and asked him to set up the elite force.

Quintana Roo state, where Cancun is located, has seen its share of officials detained for allegedly aiding drug cartels, including a former governor who was arrested in May 2001 just after he left office and was later sentenced to 36 years for money laundering and helping a drug cartel smuggle narcotics.

Former Quintana Roo governor Mario Villanueva was extradited to the United States this month to face an indictment accusing him of conspiring to import hundreds of tons of cocaine and launder millions of dollars in bribe payments through Lehman Brothers in New York and other financial institutions.