The Committee to Protect Journalists issued a statement Tuesday condemning recent attacks on a newspaper and television station in Mexico and demanding prosecution of the perpetrators.
Both incidents took place in the northern border state of Tamaulipas, a battleground for warring drug cartels.
The first attack took place March 19, when a car bomb exploded outside the offices of Expreso newspaper in Ciudad Victoria, leaving five passersby injured.
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Two days ago, an unidentified assailant hurled a grenade at the Televisa television studios in Matamoros, just across the border from Brownsville, Texas.
No one was hurt in the blast.
"The government must thoroughly investigate these attacks on Expreso and Televisa and bring the perpetrators to justice," CPJ's senior program coordinator for the Americas, Carlos Lauria, said.
"As Mexico prepares for national elections, authorities must send a clear message that they will not tolerate attacks on vital democratic institutions such as the press," Lauria said.
The attacks may have been aimed at intimidating the media ahead of the July 1 electoral contest, a journalist in Tamaulipas who spoke on condition of anonymity told CPJ.
Nearly 80 Mexican journalists have been murdered or have "disappeared" since 2000.