KUNMING - Authorities in southwest China's Yunnan Province have suspended the use of the much-disputed "laojiao" -- re-education through labor -- system, a local official has announced.

The decision, revealed on Tuesday by Yunnan Politics and Law Committee chief Meng Sutie, marks the latest step by Chinese local governments to phase out the system, which allows police to detain people for up to four years without an open trial.

Meng said Yunnan would -- with immediate effect -- stop approving cases in which people are sent to labor camps on grounds including threatening national security, petitioning by causing unrest, and smearing the image of officials.

Approval of "laojiao" for other cases are suspended, Meng said.

The official added that that those already in labor camps would continue to serve their terms.

The re-education system, established in the 1950s to rectify social order by detaining people charged with minor offences, has come in for public flak for being prone to abuse.

The controversy was highlighted by the case of Tang Hui, a woman in central Hunan Province who was sentenced to internment in a labor camp in August after demanding tougher penalties for the seven men convicted of abducting, raping and prostituting her 11-year-old daughter.

Tang was released within a week following complaints from the public and academics.

The national political and legal work conference in early January announced changes to the "laojiao" system, and they will be pushed forward this year.

In late January, south China's Guangdong Province said it planned to end the system within the year.