A subway system in western China is to carry out extensive checks after another city reported that its underground transport network failed quality tests after using the same cable supplier. The checks will be carried out on the subway system in Chengdu in Sichuan province, its operator announced on Tuesday. The vice-mayor of Xian in Shaanxi publicly apologised on Monday after its subway system failed quality inspections and eight people were detained for allegedly supplying incorrect cabling, the news website Thepapern.cn reported. Some of the electric cables for both networks were supplied by the company Aokai Cable, according to media reports. The subway network in Chengdu said four lines in its network used cables provided by the firm. The initial inspections in Xian came after a whistle-blower, said to be a former employee with the cable supplier, posted online accusing the firm of cutting back on construction materials to cut costs. Chinese subway passengers spark storm over ‘bring your own seat’ behaviour on rush-hour trains The posting said the cables in use were much smaller than needed, which would not only waste a large amount of power but could also lead to overheating and even a fire. Transport and rail safety has been a hot issue in China since 40 people were killed six years ago when two high-speed trains collided in Wenzhou in Zhejiang province. The Ministry of Railways later reported that 12 major railways including the stretch of track in Wenzhou were constructed of materials which did not meet quality requirements. The five cables which failed inspection tests in Xian were all provided by Aokai Cable and police have shut down production in all its factories, according to the news website report. Eight people have been detained for potential fraud relating to the construction materials used in the subway project, the article said. Athens in Turkey? Chinese passengers mock mistakes on subway murals The local government in Xian was quoted as saying the investigation would look into any potential collusion between the company and officials. Aokai was punished three times between 2015 and last year for producing faulty cables, Thepaper.cn said. Some social media users expressed concerns about safety on Xian’s subway system, while others praised the whistle-blower for speaking out.