Authorities in Mexico have sent troops, marines and policemen to the country's southern states after repeated instances of violence. Local elections are scheduled to take place in the region this weekend.
Violence claimed at least three candidates' lives and those of a dozen campaign workers ahead of Sunday elections for Congress, governorship and mayors' positions in Mexico.
Officials deployed policemen and soldiers in an attempt to protect polling stations. The deployment is "aimed at ensuring all Mexicans can go to the polls peacefully," the country's Interior Ministry said in a statement.
Mexicans on Sunday were to elect 500 members of the lower house of parliament, around 900 mayors and nine governors. 83 million Mexicans were eligible to vote in the polls in which President Pena Nieto's PRI party was expected to win despite scandals and difficulties in maintaining its majority in the parliament.
Officials were expecting increased violence on Sunday in the states of Guerrero and Oaxaca, where some teachers of the CNTE burned several thousand ballot papers. There were also reports of standoffs between police forces and teachers, who were protesting against a reform of the education system which called for eligibility tests.
Although the government stopped the planned implementation, teachers went ahead with protests, demanding 100 percent pay hikes and a constitutionally approved evaluation system. Protest leaders said they would block elections even if there demands were met, the Associated Press quoted local media as saying.
Security officials were also worried after two candidates for the mayor's post were killed in Guerrero and another Congress candidate murdered in Mexico City. Officials denied the possibility of drug cartels involved in the murders, with some analysts saying drug lords would profit from not being the focus of police attention for a change.
mg/bk (AFP, AP)