MEXICO CITY, Mexico (AP) -- A government human rights committee opened a memorial monument on Saturday dedicated to hundreds of missing people who presumably were abducted at the hands of police and government officials.

The Mexico City Human Rights Commission produced the glass plaque bearing the names of 557 missing Mexicans, most believed to have disappeared during the 1970s as the government carried out a campaign against guerrillas and leftist activists.

Throughout the 1970s, small groups of Marxist guerrillas attacked the army, federal agents and businessmen. The government responded with efforts to weed out suspected rebels and sympathizers -- a campaign now known as Mexico's "dirty war."

The new memorial to the missing, which spans across two large walls, was presented even as Mexican authorities continue to clash over the prosecution of former government officials involved the crackdown on activists.

Matilde Gonzalez, 78, carried on a string around her neck a picture of her son, Jesus Avila Gonzalez, last seen on April 5, 1974.

Gonzalez said the new plaque offered a needed moral boost to members of the Eureka Committee, a group of mothers of those who disappeared during the 1970s, presumably at the hands of government officials.

The committee staged its first hunger strike more than 25 years ago to call attention to disappearances.

"We still need to know what happened to them, where they wound up," Gonzalez said.

Armando Otto Gaytan, 55, said he met some of the people who remain missing after his arrest in 1979, when he spent nine months in the basement of a military jail.

"It's moving, and emotionally experience," said Gaytan, examining the list of names, each accompanied by a disappearance date. "This should not be forgotten."

President Vicente Fox has appointed a special prosecutor to investigate the conduct of government officials in the crackdown on political dissidents.

Last month, a federal judge refused to issue an arrest warrant against former President Luis Echeverria, who faces genocide charges for the killing of protesters in a clash with pro-government thugs during a 1971 demonstration.

Copyright 2004 The Associated Press.