More than half China's drug factories will have to improve their waste disposal or face shutdown under the first pollution standards for the industry to be unveiled this year, state media said on Wednesday.

China's environmental watchdog has closed down or suspended 649 firms and given dozens of others a deadline to clean up their act, state media had said earlier, amid growing concern about pollution ahead of the 2008 Olympics.

The State Environmental Protection Administration launched a two-month campaign in July to clean up the country's heavily polluted rivers. Now it is targeting drug factories specifically.

Current standards for industrial waste water and emissions were set in the 1990s, with no specific rules or requirements for pharmaceutical companies, the China Daily said.

Due to fierce competition, and to minimize costs, drug companies tend not to prioritize waste control and environmental protection, Zhang Buyong, of the Guangzhou-based South Medicine Economic Research Institution, was quoted as saying.

Of the list of 6,066 heavily polluting companies published in March by the State Environmental Protection Administration, 117 were pharmaceutical firms.

Polluters along two of China's main rivers have defied a decade-old clean-up effort, leaving much of the water unfit to touch, let alone drink, and a risk to a sixth of the population, state media said last week.

Half the check points along the Huai River and its tributaries in central and eastern China showed pollution of Grade 5 or worse -- the top of the dial in key toxins, meaning that the water was unfit for human contact and may not be fit even for irrigation, national legislators were told.