More than 20 high-speed railways constructed since 2005 have substandard components, according to a state media report that puts the embattled network back in the spotlight.
Tests found that the faulty parts connected structures like pipelines to the concrete sections of tunnels.
People.com.cn, which is affiliated with the official People's Daily, reported on Wednesday that laboratory tests suggested that the components, called 'cast-in channels', being used in the construction of the Shanghai-to-Kunming high-speed railway failed to meet national quality standards.
The metallic components, which the website said were taken by reporters from the construction site, failed a number of tests, including for stress, minimum tensile load and fire resistance.
The railway authorities said they have launched an investigation into possible irregularities in connection with the cast-in channels, the website reported.
Peng Zhihua, a laboratory technician with the Ministry of Public Security, who focuses on making materials more resistant to fire, noted in the report the dangers associated with using substandard products in large-scale projects such as the high-speed railways.
Although production certificates by German company Halfen - which makes fixing systems and building products for the construction industry - indicate that the firm made the cast-in channels in Germany, whistle-blowers were quoted in the report as saying that the company actually made the components in China.
By saying the components were made abroad, the company could sell them to the Ministry of Railways at a 30 per cent mark-up over domestic prices, the report said.
'The 333-kilometre Shanghai-to-Kunming high-speed railway could have purchased more than 80 million yuan [HK$97.9 million] worth of cast-in channels from Halfen,' the report said, adding that the German firm supplies 70 per cent of cast-in channels for China's high-speed rail industry.
But Halfen's Beijing-based China headquarters denied the accusations in a statement sent to the South China Morning Post yesterday.
'These reports contain false, erroneous and incomplete information. ... Halfen will continue to take all legal measures and actions to clarify and provide the real facts to the public, as well as to firmly protect the reputation of Halfen in China, which is being unfairly tainted,' the statement said.
Halfen said all channel profiles sold in China are made and imported from Germany, and that they are approved by the Chinese and German authorities.
The mark-up over Chinese prices which Halfen could earn when selling its components, by saying they were made in Germany