The National quality watchdog Thursday warned of "severe punishment" to anyone found responsible for the collapsed school building in the May 12 earthquake.

Inspectors have taken samples of rubble to see if shoddy construction material was used, according to an official of the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).

"It's regretful to see so many young students die ... and inspection teams have been sent to the disaster-hit areas to take samples of school debris," Zhi Shuping, deputy director of the AQSIQ told a news briefing.

Zhi said the investigations had so far yielded no results, but "if they show quality problems do exist, we'll deal with those responsible with zero tolerance."

The AQSIQ also pledged swift and severe punishment for suppliers seeking to profit from the masssive reconstruction with sub-standard goods.

Lin Qiang, vice inspector of the Sichuan provincial educational department, said "seeking truth is more important than losing face."

The collapsed buildings might have been more solid "if we educational officials hadn't left loopholes for corruption", the Xinhua news agency quoted Lin as saying.

He withdrew as torch bearer in the torch relay currently snaking around China before the August Olympic Games in Beijing.

The death toll from the 8.0 magnitude quake is over 68,500 and is certain to rise further, with 20,000 missing.

Many children - official figures are not available - were crushed to death in collapsed buildings. Some parents have blamed the tragedy on shoddy construction quality.

On Sunday, more than 100 parents - whose children were killed in the collapse of the Fuxin No 2 Primary School in Mianzhu city - marched downtown with placards bearing slogans and photographs of their children, questioning construction quality, Xinhua reported.

Meanwhile, rescuers Thursday battled rain to drain a "quake lake" threatening to burst its banks and cause floods.

Rain has hampered efforts by more than 600 soldiers to open a giant sluice to discharge floodwaters. Helicopters shipping in equipment were unable to take off, and some 1,000 soldiers had to carry in 10 tonnes of diesel by foot to fuel bulldozers there.

About 133,000 troops and armed police are in the disaster area, said Lu Dengming of the Chengdu Military Area Command.

Heavy rains could further complicate rescue work by swelling the lakes, triggering mudflows, and adding to the misery of 5 million left homeless.

China has evacuated more than 150,000 people living below the biggest of the quake lakes at Tangjiashan. It was created when landslides blocked the Jianjiang river above Beichuan, near the epicentre.

The Finance Ministry has funnelled an extra 1 billion yuan ($144.2 million) into relief work on an estimated 35 dangerous lakes formed by landslides, in addition to 400 million yuan already alloted to work on smaller, damaged dams.

A massive relief effort, which involves providing food, tents and clothing for millions and the reconstruction of housing and infrastructure, including the many destroyed schools, is expected to take up to three years.

China enacted a special statute to punish fraud and misuse of relief goods and donations, and sent 300 auditors to the area.

Donations from home and abroad had reached 37.3 billion yuan ($5.38 billion) by Thursday, up 2.5 billion yuan from the previous day, the Information Office of the State Council said.

(China Daily/Xinhua May 30, 2008)