The National Action Party, or PAN, and Party of the Democratic Revolution, or PRD, Mexico's main opposition parties, have called on President Enrique Peña Nieto's administration to deal with cases of violence ahead of the local elections in 14 states.

"We see a tense electoral climate, not just because of the endless irregularities that have occurred and that continue occurring eight days ahead of the elections, but also because of the climate of violence against candidates, relatives and leaders," PRD secretary-general Alejandro Sanchez Camacho said during a rally on Sunday.

The PRD is ready for the July 7 elections despite the violence and lack of fairness in the process, Sanchez Camacho said.

PRD official Nicolas Merino was kidnapped and murdered in Tuxtepec, a city in the southern state of Oaxaca last week.

The conservative PAN, meanwhile, also called for an end to the pre-election violence.

The wave of violence of the past few days is "regrettable" and "sad," PAN chairman Gustavo Madero said during a visit Sunday to the central state of Aguascalientes.

"This issue should be dealt with by going beyond the partisan differences to find a solution among all of us," Madero said.

Some 30 million Mexicans will be eligible to vote in the elections next Sunday, when nearly 1,800 offices in 14 states will be up for grabs.

A total of 1,348 mayoralties and more than 400 state legislative seats will be in play in the elections. EFE