Marchers block Mexico-US border
Hundreds of people in Mexico have blocked key crossings into the US in protests against the deployment of the army fighting drug traffickers.
Traffic was brought to a halt on a number of bridges in several border towns in northern Mexico.
The protesters accused the army of abuse against civilians. Government officials said the blockades had been organised by drug gangs.
The army was sent into border towns in 2006 to control rising drug violence.
Violence continued on Tuesday in the border town of Ciudad Juarez where three police officers were shot dead by unidentified gunmen.
More than 5,000 people were killed in drug-related violence last year, Mexican officials say.
Powerful drug cartels have been fighting both each other and federal forces as they battle to control the immensely lucrative routes trafficking cocaine and other drugs from Colombia to the US via Mexico.
Up to 40,000 troops are currently deployed against trafficking cartels.
In some parts of the country, the army has taken over the role of the police, which have often proved easily corrupted when bribed or threatened by the gangs, says the BBC's Stephen Gibbs in Mexico City.
The protesters blocked bridges in Ciudad Juarez, Nuevo Laredo and Reynosa.
They chanted "Soldiers out!" and "Stop abuse by the PFP [Federal Preventative Police]!"
The demonstrators also shut roads in the industrial city of Monterrey.
Many of the protesters said border towns had become more dangerous since President Felipe Calderon sent the army in three years ago.
But the governor of one state - Nuevo Leon - said he believed the Gulf drugs cartel and its armed wing, the Zetas, were behind the border protests.
"There are reasons to believe it has to do with the Gulf cartel and the group known as the Zetas," Governor Natividad Gonzalez said.
Human rights activists say there are legitimate complaints about reported abuses by the troops, including alleged cases in which army patrols have fired on civilians at checkpoints.
President Calderon has deployed tens of thousands of troops along the border, vowing to destroy drug cartels.
Protesters accuse the army of abuse against civilians
Huge quantities of Colombian cocaine are sent to the US via Mexico