BEIJING, DEC. 28 -- China's public security minister, who was blamed for ineffective police control during last year's demonstrations for democracy, has been replaced by one of his deputies, authorities announced today.

Officials also replaced the foreign trade minister, approved China's first law safeguarding the rights of the disabled, and toughened penalties for trafficking in drugs and pornography, imposing the death penalty for pornography cases deemed "serious."

The actions were taken by the standing committee of China's nominal legislature, which just concluded a nine-day session, the official New China News Agency reported.

Vice Minister Tao Siju, 55, believed to be a close associate of Premier Li Peng, was named to replace Public Security Minister Wang Fang, 70. No reason was given for the personnel change, but the news agency said Wang had previously submitted his resignation.

Wang's replacement has been rumored ever since the student-led demonstrations, which ended with an army crackdown that left hundreds dead in June 1989. Many public security officers and the paramilitary People's Armed Police, also under Wang's control, were considered sympathetic to the student movement.

Wang, a close ally of ousted Communist Party leader Zhao Ziyang, was blamed for allowing the demonstrations to spin out of control and for allowing several student leaders and other democracy activists to escape to the West.

According to a recent report in a Hong Kong magazine, Wang's daughter, who was studying at a university in Beijing last year, briefed her father on the students' situation and urged him not to "do anything against the interests of the people."

Wang, who was formerly Communist Party secretary of Zhejiang province, in eastern China, was appointed public security minister in 1987 in a move that was opposed by the party's hard-liners, the magazine said. His removal was delayed because of intense struggles within the intelligence apparatus, it said.

Wang's replacement, Tao, has been a vice minister of public security since 1983 and accompanied Premier Li Peng during his visit to four Asian countries this month.

In the other ministry change, Foreign Trade Minister Zheng Tuobin, 66, who has spent most of his career in foreign trade, was replaced by one of his vice ministers, Li Lanqing. Zheng was appointed to the top job in 1985 and was considered to be an active supporter of economic reform.

No reason was given for the change, although one Chinese source said Li may be more acceptable to the hard-liners in the current leadership than Zheng.

Li, 58, has worked in the auto industry and was a vice mayor of Tianjin, serving under then-mayor Li Ruihuan, a leading proponent of economic reform and now a member of the six-man standing committee of the Politburo, the party's highest decision-making body. Li Lanqing became a vice minister at the Foreign Trade Ministry in 1986.

The legislature's standing committee also adopted a resolution that provides for the death penalty or life imprisonment for "serious cases of smuggling, production, sale or distribution" of pornographic material. Books on anatomy, and literature and art works containing sexually explicit materials, would not be considered pornographic.