About 30 candidates for elections taking place in Mexico in July have already been murdered, Interior Minister Alfonso Navarrete said Monday.

Those targeted were mostly hoping to contest mayoral and regional parliamentary seats, according to Navarrete, with the southwestern state of Guerrero one of the worst affected by violence.

On July 1, Mexicans will elect a new president, national parliamentarians in both chambers, regional parliamentarians, eight governors and mayors including for Mexico City.

Criminal gangs fueled by drug money often seek to control politics, particularly on a local level, and target politicians who might take action against them.

The country suffered its bloodiest year in two decades last year, with 29,000 murders recorded.