BEIJING (AP) _ The Chinese government has frozen a fund created for victims of the Tiananmen Square democracy demonstrations in 1989, according to the mother of a boy who was killed in the assault.

The New York-based group Human Rights in China Monday quoted Ding Zilin as saying that she has been unable to withdraw donation money from the bank. Ding, who has led efforts to help those injured or who lost relatives when the military suppressed the demonstrations, collected the money from Chinese overseas students and others in Germany last year.

In a letter addressed to President Jiang Zemin, Premier Zhu Rongji and U.N. Human Rights Commissioner Mary Robinson, Ding said officials were ``brutally trampling on the rights of citizens.''

Ding discovered last week that the State Security Bureau recently froze the funds for another six months until April, the human rights group said.

In a separate development, dissident Bai Xiaomao, a member of the banned China Democracy Party in the city of Chenzhou in Hunan province, was detained by police on Sunday, the Hong Kong-based Information Center of Human Rights and Democratic Movement in China said.

Bai was a factory worker who served eight years in prison for his involvement in the 1989 democracy demonstrations.

In the northeastern province of Liaoning, authorities prevented another member of the would-be opposition party, Liu Shizun, from seeing his lawyer, the center said.

Liu, a former leader of the student protests, was detained in September after police ransacked his home looking for phone records and other material. He has been charged with subversion.

Authorities began cracking down on members of the China Democracy Party and other dissidents late last year. Many have been sentenced to lengthy jail terms.