Mexican police have rescued two of four kidnapped journalists that were abducted by alleged drug gangs earlier in the week, officials have said.

Alejandro Hernandez, a cameraman for Mexico's biggest televesion network, Televisa, and Javier Canales, another cameraman for Multimedios Television,  were freed on Saturday after a police raid in the northern city of Gomez Palacio.

"They were rescued today," the ministry of security said in a statement.

Local media said one of the kidnapped journalists, Hector Gordoa, a reporter for Televisa, was freed on Thursday.

The four journalists were kidnapped on Monday after covering a prison scandal in the northern state of Durango in which inmates are accused of being hired guns for a local drug cartel.

Attacks on the media have mounted as drug gangs seek to silence journalists who report on the drug-related killings.

Since 2006, at least 30 journalists have been killed in Mexico, according to Mexican media.

Mexico is considered to be one of the world's most dangerous countries for the media.