Tamoulipas: The number of journalists who lost their lives in the brutal attacks of drug gangs is increasing in Mexico.

Country's most violent northern border states in Tamoulipas, Mexican journalist Antonio de la Cruz, 47, was murdered in the latest of a series of attacks on reporters. His murder may be linked to his criticism of politics.

De la Cruz was shot and killed in his home in the Tamaulipas state capital Ciudad Victoria, the paper he worked for said.

The journalist's daughter was injured in the attack. Tamaulipas Governor Francisco Garcia Cabeza de Vaca said the young woman was in critical condition.

"We're not going to stop until we find those responsible, and we're going to punish them with the full weight of the law," the governor said.

President Andres Manuel Lopez Obrador's spokesman Jesus Ramirez Cuevas posted on twitter about the assassination.

Tamaulipas attorney general's office said in a statement it had opened an investigation and police were collecting evidence and searching for the attackers.

Tamaulipas is a gulf coast state, just south of Texas, where violent drug cartels fight over lucrative smuggling routes.

Local journalists who focus on crime and corruption are especially vulnerable.

De la Cruz's death follows at least eight other media workers who have been murdered in Mexico this year as a result of their journalism, according to human rights organisation Article 19.

Violence against the press has skyrocketed during Mexican President Andres Manuel Lopez Obrador's administration, according to a report published by Article 19.

-ABC