OAXACA, Mexico, Jan 30 (Reuters) - Gunmen shot dead a local police chief and three other people on Wednesday in Oaxaca, a politically tense southern Mexican city where leftists held a months-long siege in 2006.

Oaxaca state Gov. Ulises Ruiz said the murders were linked to drug smuggling cartels whose violent turf wars killed more than 2,500 people across Mexico last year.

Local police chief Alejandro Barrita was in charge of police units guarding banks and businesses on Oaxaca, a pretty colonial city still scarred by the protests of 2006.

Barrita was killed while he was exercising in a city park. The gunmen also killed his bodyguard and two other people doing exercise in the park, state police director Daniel Camarena told reporters.

Ruiz said the killings were a response to the increased military presence in Oaxaca. President Felipe Calderon has sent 25,000 troops across Mexico to try to control the escalating violence between rival drug gangs.

"This is a result of the fight against organized crime and ... is causing the deaths of our police chiefs," Ruiz told local radio.

Camarena said he was also investigating other motives.

Mexican rebel group Popular Revolutionary Army, or EPR, bombed natural gas and oil pipelines in 2007 to demand the release of two leftist activists it says were seized by the government in May in Oaxaca.

Oaxaca, a popular stop for European and U.S. tourists, in 2006 faced a violent conflict between state police and protesters calling for Ruiz to resign. (Reporting by Paulina Valencia; Editing by Cynthia Osterman)

AlertNet news is provided by