The daughter of a top Chinese Communist Party official has apologised over the killing of one of her teachers, the latest former Red Guard to express remorse for the horrors of Mao Zedong's Cultural Revolution, state media said Monday.

Song Binbin's father Song Renqiong was a powerful general and one of the Communist Party's "Eight Immortals", and she herself was a leader of the revolutionary Red Guards at her school as a teenager in 1966.

The establishment's vice-president Bian Zhongyun was beaten to death in one of the first and most notorious killings of a teacher during China's decade of chaos and bloodshed.

Now 64, Song says she should have done more to protect Bian and other school officials -- although she did not specify her exact role in events.

"Please allow me to express my everlasting grief and apologies to Principal Bian," Song said Sunday in a tearful apology at her former school, the Beijing News reported on Monday.

"I failed to protect the school leaders, and this has been a source of lifelong pain and remorse."

"If we don't reflect on things, it is hard to get close to the truth," she told the newspaper. "I hope that all of those who made mistakes during the Cultural Revolution -- all those who did harm to their teachers and classmates -- can face themselves, reflect on the Cultural Revolution, ask for forgiveness and achieve reconciliation.

"I believe this is everyone's desire."

China heavily censors discussion of the Cultural Revolution, the decade of social and political upheaval led by Mao during which millions were persecuted and killed.

But in recent months, several former Red Guards -- members of the student movement charged with purging the country of ideological "foes", often by bloody means -- have stepped forward to apologise for their actions.

Last October, Chen Xiaolu, a former Red Guard leader and the son of a legendary Communist military leader, visited his former school in Beijing to offer his remorse to teachers and staff who had been tortured and subjected to forced labour.

Such "inhumane violations of human rights should not appear again in any form in China", Chen wrote in a blog post months before he delivered his face-to-face apology.

While some in China greeted Song's apology Monday, Wang Jingyao, the slain teacher's widower, said that she did not go far enough and that a fuller accounting of her part in the killing was in order.

"She is a bad person, because of what she did," Wang was quoted as saying by the New York Times. "She and the others were supported by Mao Zedong. Mao was the source of all evil. He did so much that was bad... The entire Communist Party and Mao Zedong are also responsible."