Police used excessive force during a march to commemorate the 45th anniversary of a massacre of student protesters in the Mexican capital, human rights organizations said Thursday.

"We have all the violations documented," the president of the Mexican League for the Defense of Human Rights, Adrian Ramirez, told a press conference.

Wednesday night's march in Mexico City was largely peaceful, though the municipal police department said 32 of their officers were injured in clashes with hooded anarchists.

Police acted in "strict conformity with the applicable norm for crowd control," the Mexico City Public Safety Department said.

But the human rights groups say police violated their own regulations by using tear gas and rubber bullets against peaceful protesters.

While expressing solidarity with the injured police officers, Dario Ramirez, head of the Mexico chapter of Article 19, said it was a grave matter "that the state assaults protesters."

"What we saw yesterday was clearly a rather unprofessional police (force)," he said, citing 22 documented instances of police aggression against journalists covering the march.

Two of the journalists assaulted by the cops, Gustavo Ruiz Lizarraga and Pavel Alejandro Primo, were arraigned Thursday on charges of disrupting the peace, Ramirez noted.

"We firmly condemn violence, whatever the source," the director of the Miguel Agustin Pro-Juarez Human Rights Center, Jose Rosario Marroquin, said during the press conference.

Mexico, he said, is experiencing a "pattern of repression" that extends to journalists, human rights monitors and "anyone who is documenting the conduct of the authorities."

Observers saw plainclothes police making arbitrary arrests and acting as provocateurs at the march, the rights organizations said.

The march began in Tlatelolco square, where a few dozen soldiers and paramilitaries opened fire on a peaceful student rally the evening of Oct. 2, 1968.

Efforts to hold anyone in authority accountable for the killings have been frustrated by the courts and by Mexican institutions' persistent unwillingness to hand over information.

Even the death toll remains a matter of dispute. Authorities released only 44 bodies, but activists say as many as 400 were slain. EFE