Citing ministry sources, the 21st Century Business Herald reported yesterday that Beijing planned to curb COD emissions by 5 per cent by 2015 from the 2010 level and set a 10 per cent control target for acid-rain-causing sulphur dioxide, the other binding indicator in the current plan.

'It is quite shocking to see such a big drop in the proposed COD targets for the next five-year plan,' the report quoted an unnamed scholar at the Policy Research Centre for Environment and Economy, a ministry think tank, as saying.

Dr Chen Sai, another researcher at the centre, confirmed the reported targets, saying they were based on comprehensive studies of the country's environmental capacity and economic development.

'It is right to say that it would become a lot more difficult to substantially cut pollution on the basis of what we have achieved in the past years, which is quite remarkable in our eyes,' she said.

Beijing's high-profile pollution control campaign began in 2006 amid much fanfare with ambitious targets to cut the two indicators by 10 per cent before the end of this year.

But the campaign, which Beijing said was its biggest contribution to the international effort against global warming, suffered major setbacks in the wake of the global financial turmoil, when economic recovery became the overriding priority for local authorities.

While the mainland met its target for curbing sulphur dioxide emissions a year ahead of schedule, the ministry admitted this year it would have difficulty hitting the COD target. But it remained confident about meeting its commitment.

Ma Jun, a water pollution expert, said the reduced targets for the next five years underlined the constraints of the government's administrative power in tackling widespread pollution woes. 'Although we have seen progress in controlling COD emissions in some industrial sectors, its discharge in many residential areas has risen,' he said, citing his online pollution database.

Authorities also admitted COD emissions on the mainland had far exceeded the country's environmental capacity despite the costly cleanup effort.

'We certainly wish the government had set higher, more ambitious targets. But it will never be enough for the government to act on its own with command-and-control policies. The government should look for other alternatives,' he said.

Beijing should introduce market-oriented mechanisms and increase transparency in pollution control to enlist public support, he and other environmentalists said.

Chen at the think tank agreed, saying controlling COD was far from enough to clean up the country's polluted rivers and lakes. 'COD has far less impact on human bodies than some other indicators, such as toxic chemical pollutants and heavy metals,' she said.

Wang Yongchen , of Beijing-based Green Earth Volunteers, said it would be a shame if the report on lowered targets was confirmed in the lead-up to the United Nations climate change conference in Cancun, Mexico. The targets will be officially unveiled in March during the annual National People's Congress session.