BEIJING (AFP) - Rights group Amnesty International has urged China to end what it called the harassment of parents seeking to find out how their children died in last year's Sichuan earthquake.

In a new report ahead of next week's one-year anniversary of the quake, which left nearly 88,000 people dead or missing, the watchdog documented cases of the government detaining parents who tried to question officials.

Thousands of students were believed to have been killed when their shoddily built schools collapsed in the quake.

"The government of China must cease harassing earthquake survivors who are seeking answers and trying to pick up the pieces of their shattered lives," said Roseann Rife, Amnesty's Asia-Pacific deputy programme director.

"By unlawfully locking up parents of children who died, the government is creating more misery for people who have said in some cases they lost everything," she said in a statement.

A year after the May 12, 2008 quake, the government has still not released the total number of school-aged victims and has appeared eager to cover up alleged corruption in the building of numerous schools.

Amnesty called for the lifting of restrictions on families seeking legal redress, including compensation for poorly built schools.

Chinese Human Rights Defenders, a group of China-based activists, has meanwhile urged the government to release two people, Huang Qi and Tan Zuoren, who were jailed in recent months after investigating school collapses.

In a statement the group called on the Chinese government to "make public its own assessment of the conditions of the collapsed school buildings and a comprehensive list of student casualties."

The government has pledged to investigate all school collapses but so far no report has been made public.