An interior document from the Ministry of Railways said 12 railway lines, including five lines under construction, have quality defects that endanger safety, The Economic Observer reported on its website on Aug 7.

The document said a notice of criticism was circulated internally, and relevant corporations building those railways had their qualifications for tendering and bidding suspended, and were required by authorities to rectify the problems within a set timeframe.

The document was confirmed by an anonymous source close to the ministry, the report said.

The 12 railway lines include seven railways that are already in service: the Wuhan-Guangzhou passenger line, Ningbo-Taizhou-Wenzhou line, Zhengzhou-Xi'an passenger line, Hainan east ring intercity rail, Wenzhou-Fuzhou line, Fuzhou-Xiamen line and the Nanchang-Jiujiang line.

The seven railways in service were said to have different levels of quality problems, which endanger safe operations, the report said.

Some railways had already experienced major accidents, such as the Ningbo-Taizhou-Wenzhou line. The five railways under construction were criticized for using substandard rail lines.

The document, dated Aug 1, revealed construction defects in tunnel arches, communication towers and railroad building equipment, poor arrangement of electronic cables, and missing rebar in reinforced concrete in certain lines.

By noon on Aug 8, the Ministry of Railways had not made any statement about the document.

In February, Minister of Railways Sheng Guangzu said at a conference that railway construction is a high-risk area in terms of controlling quality and preventing corruption.

The Ministry of Railways recently announced details of disciplinary violations by former minister Liu Zhijun, who made huge illegal profits helping others bid for several railway projects, according to media reports.