China's much-vaunted abolition of its widely loathed "re-education through labour" camps risks being no more than a cosmetic change because of other rights abuses, Amnesty International said Tuesday.

Arbitrary detention will persist in unofficial "black jails", drug rehabilitation centres and other facilities, the rights group said in a report.

The "re-education through labour" scheme, known as laojiao, was first instituted in the 1950s by the ruling Communist Party, which announced last month it plans to dismantle the system.

Under it, police panels can sentence offenders to up to four years in camps without a trial. It is largely used for petty offenders but is also blamed for rights abuses by officials seeking to punish "petitioners" who try to complain about them to higher authorities.

Amnesty welcomed the move but added: "Human rights defenders, democracy advocates, whistle-blowers and other political activists are being increasingly targeted through criminal detention, 'black jails', short-term administrative detention, and enforced disappearances."

There was a "very real risk that the Chinese authorities will abolish one system of arbitrary detention only to expand the use of other types" unless there was "a more fundamental change in the policies and practices that drive punishment of individuals and groups for nothing more than exercising their rights", it said.

The Amnesty report was based on more than 60 interviews conducted over the past four years with former labour camp inmates and other detainees, "most of whom were subjected to torture and other ill-treatment in detention", the group said.

A number of labour camps in Xinjiang, Jiangsu, Sichuan, Jilin and other provinces have been renamed as drug treatment centres offering "very little in the form of drug rehabilitation", it said.

They were operating "virtually identically" to laojiao facilities "where detainees can be held for years of harsh forced labour and ill-treatment", it said.

China says that it attaches great importance to human rights and that any detentions are carried out in accordance with the law.

The United Nations estimated in 2009 that as many as 190,000 people were held in the laojiao camps.

Pressure to change the deeply unpopular system has been mounting for years, and China's Communist Party leaders announced after a key gathering in Beijing last month that they would move to abolish it.

But they have so far released few details of how they plan to implement the change.

The Standing Committee of the National People's Congress, China's rubber-stamp parliament, is expected to take up the issue next week, the official Xinhua news agency reported Monday.