Tests by China's top quality control watchdog have found that the strength of the suspect tubes did not meet standards while in some cases the valves were not attached to the tubes firmly enough, Xinhua news agency said.

After an initially defensive response to a string of product-quality problems that have tarnished the "made in China" label worldwide, China has recently taken steps aimed at rooting out producers of shoddy goods.

The General Administration of Quality Supervision, Inspection and Quarantine checked 51 truck tyres and tyre tubes produced by 30 companies across the country, Xinhua said.

It said all of the Chinese-made tyres passed muster, but the tube deficiencies meant they were liable to explode once in use.

None of the tubes was destined for the export market, it said.

Chinese-made tyres are just one of the many products whose safety has been questioned in recent months amid mounting reports of dangerous Chinese food and other goods exported to the United States.