China Railway Corp discovered some tunnels along the Shanghai-Kunming high-speed railway have some serious quality problems, which pose safety risks to the line, Thepaper.cn reported on Tuesday.

China Railway Corp investigated some tunnels in the Guizhou section of the Shanghai-Kunming high-speed railway and found some serious problems, such as fake construction materials, said?a netizen called "Headlines in Guizhou" on Sina Weibo, a Chinese Twitter-like service, on Monday.

The company confirmed that?what the netizen said?is true, Thepaper.cn reported.

Companies involved in the tunnels' construction, design and inspection all received punishment.

The original post was no longer online on Tuesday morning.

The 2,252-kilometer rail line opened in late December and is the nation's longest east-west high-speed railway. It traverses five provinces - East China's Zhejiang and Jiangxi, Central China's Hunan and Southwest China's Guizhou and Yunnan - and cuts the rail travel time between?Shanghai and Kunming?from 34 hours to 11.