Nine polling company workers - six employees of Consulta Mitofsky and three staffers from Parametria - were released by the unidentified group that kidnapped them in western Mexico, an executive said Wednesday.

The pollsters all disappeared in Apatzingan, a city in the western state of Michoacan where the La Familia and Los Caballeros Templarios drug gangs operate.

The Consulta Mitofsky employees disappeared on Saturday, while the Parametria workers went missing around noon on Monday.

The Consulta Mitofsky workers were freed and are fine, the company's chairman, Roy Campos, said in a Twitter posting, without providing additional details.

"Yes, it's been confirmed, I celebrate the release of the 6 persons that were doing polling, I do not celebrate that they had several days taken from them," Campos said.

The Consulta Mitofsky workers had gathered in the area to poll voters on their preferences among the Party of the Democratic Revolution, or PRD, candidates vying for the mayoralty of Apatzingan.

Campos reported a few hours later that the three Parametria workers, who had gone missing around the community of La Nopalera, had also been released.

I want to thank "the police officers, the soldiers and the civilians who helped" search for the missing workers, Campos said.

"The five male pollsters and the female pollster, who are now free, are not involved in any conflict and are just part of the group of Mexicans who live and work for our country," the executive 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 the death of one of its top bosses, Nazario Moreno, 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 Los Caballeros Templarios in March.

The federal government deployed 1,800 additional Federal Police officers in Michoacan, President Felipe Calderon's home state, in early July to fight the state's criminal organizations.

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.