A candidate in next week’s regional elections in Mexico has been critically injured in a gun attack in the south of the country.

Rosalia Palma, a candidate of the governing PRI party for the Oaxaca state assembly, was hit when her vehicle was fired on, officials said.

Her husband and an aide were killed.

Violence has marred the election campaign, the first since President Enrique Pena Nieto came to power last December.

He has promised to review Mexico’s “war on drugs” policy.

More than 70,000 people are estimated to have died in drug-related violence under the presidency of Felipe Calderon between 2006 and 2012.

Saturday’s attack comes two days after the leader of the left-wing Democratic Revolution Party (PRD) in Oaxaca, Nicolas Estrada, was found dead with gunshot wounds.

On Friday, two candidates in the Pacific coast state of Sinaloa dropped out of the race after a member of their coalition was killed.