BEIJING — In a step toward rule of law, China's national legislature on Saturday voted to abolish a much-criticized penal system that allowed police to lock up people for up to four years without due process.

The standing committee of the National People's Congress adopted a resolution to abolish the re-education labor system, formalizing a November decision by the ruling Chinese Communist Party, according to the official Xinhua News Agency and the state-run China Central Television.

State media said all those serving time in the labor camps would be set free starting Saturday, but that the penalties handed out before the abolition would still be considered legitimate, a provision aimed at preventing the victims from suing the state and seeking redress.

Established to punish early critics of the Communist Party, the penal system was retooled to focus on petty criminals. In recent years, however, it had been used by local officials to deal with people challenging their authority on issues including land rights and corruption.

"It has become a tool of revenge and retaliation," Wang Gongyi, a former director of a research institute under the Chinese Ministry of Justice, said earlier this year.

The country's senior leadership signaled its intention to end the system in January, and labor camps throughout China stopped admitting people since March, legislative official Lei Jianbin told CCTV on Saturday.

Chinese officials, however, remained coy about their plans to dismantle the penal system until November, when the party announced that it would abolish the camps.