A search is underway for six employees of polling firm Consulta Mitofsky who disappeared over the weekend near Apatzingan, a city in western Mexico, the Michoacan state Attorney General's Office said.

A team of 36 employees of the polling firm were staying at a hotel in Apatzingan, an AG's office spokesman told Efe, adding that when three of them failed to return at the end of the day on Saturday, three others went searching for the missing workers.

Consulta Mitofsky, which is led by Roy Campos, registered a complaint on Sunday afternoon with the prosecutor's office in the Tierra Caliente region and filed missing person reports, the AG's office spokesman said.

"A complaint has been filed for illegal deprivation of freedom and/or what happened," the AG's office spokesman said.

The missing Consulta Mitofsky employees are five men and a woman, Radio Formula reported.

The first group of missing pollsters was sent to gather information on political views in the town of La Cofradia, which is located in an area that has been battered by drug-related violence in the past few months.

The polling company workers may have gotten lost in an area that they do not know well, police said.

Michoacan has been experiencing a wave of drug-related violence blamed on the break-up of La Familia Michoacana, which was considered one of Mexico's most powerful drug cartels.

La Familia has been severely weakened in recent months by infighting and government operations targeting the gang.

The cartel began unraveling after cartel boss Nazario Moreno's death last year, officials and analysts say.

Moreno, known as "El Chayo" and considered La Familia's ideological leader, was killed in a shootout with the Federal Police in December 2010.

The La Familia faction led by Jesus Mendez, who was arrested in June, has been fighting the group led by Servando Gomez and Enrique Plancarte, who formed the Los Caballeros Templarios cartel in March.

Los Caballeros Templarios, like La Familia, requires members to adhere to a code of conduct and portrays itself as working for the good of the community despite its criminal activities.

Michoacan is on Mexico's Pacific coast, which is used by smugglers to bring drugs into the country.

The drugs are then smuggled via the Pacific corridor or through central Mexico into the United States, the world's largest consumer of illegal drugs.