China is to abolish its controversial "re-education through labour" system, under which police panels can sentence offenders to years in camps without a trial, the official Xinhua news agency said Friday.

The move was "part of efforts to improve human rights and judicial practices" it said, and came in a detailed reform statement issued after a key meeting of the ruling Communist party that ended earlier this week.

The gathering, known as the Third Plenum, had also decided to reduce "step by step" the number of crimes subject to the death penalty, Xinhua added.

The deeply unpopular labour camp system, known as "laojiao", is largely used for petty offenders but is also blamed for widespread rights abuses by corrupt officials seeking to punish whistleblowers and those who try to complain about them to higher authorities.

Under the scheme, people can be sent for up to four years' "re-education" by a police panel, without a court appearance.

It was introduced in 1957 as a faster method of handling minor offences.

A 2009 United Nations report estimated that 190,000 Chinese were locked up in such facilities.

Life in the camps can vary widely, but many prisoners face extremely long work days manufacturing goods or doing agricultural work, the Duihua Foundation, a US-based rights group, said in a report.

Pressure for change in the system has been building for years.

The national parliament has considered reforms to the system since at least 2005 but not passed related legislation.

In a high-profile case in August last year, Tang Hui, a mother from central Hunan province, was sentenced to a labour camp for petitioning repeatedly after her 11-year-old daughter was kidnapped and forced to work as a prostitute.

Tang had sought accountability for police officers that she said aided the culprits. She was freed after just over a week following a public outcry.

The next month a man in the southwestern metropolis of Chongqing -- who served two years in a labour camp for mocking an aggressive campaign that put thousands of people behind bars -- was ruled by a local panel to have been sentenced unlawfully.

After China's new leadership under Xi Jinping took charge of the Communist party in November last year, speculation about possible reform mounted.

State media said in January that the system would be abolished, but the reports were swiftly deleted and replaced with predictions of reform, with few details and no timetable.

Four pilot cities replaced re-education through labour with a system called "illegal behaviour rectification through education", the Beijing News said later, without explaining the differences between the two systems.

Premier Li Keqiang said at a major gathering of the national parliament in March that details might be unveiled by year's end.

It was not immediately clear Friday how it would be replaced.

But analysts say the abolition of the system could face resistance as local governments profit from products made by camp prisoners and rely on the punishment to keep social order.