Eight people at an electric cable company in Xi'an, Shaanxi province, have been detained for providing substandard electric cables for the city's subway.

Wang Zhiwei, a legal representative of the company, knelt down and apologized to the public for providing the products, according to Xi'an Release, a WeChat account of the city government.

The company, Shaanxi Aokai Cable Co, has been shut down and its main owners as well as several managers have been detained.

The government of Xi'an held a news conference on Monday and announced the result of an investigation into an electric cable project on the city's subway Line 3.

"All of the five samples of the low-voltage cables from subway Line 3 failed to meet set standards," said Jin Qun, deputy head of the National Wire and Cable Products Quality Supervision and Test Center.

Zheng Xiaoquan, a professor of electrical equipment insulation at Xi'an Jiaotong University, said that the substandard cables were only used in part of the system and do not affect subway safety or operations.

However, the metro company said at the news conference that it will replace all the substandard cables.

Yang Xin, head of the commission for discipline inspection in Xi'an, the city's top anti-graft authority, said an investigation examined the project's data and documents, and looked into the supervision work by administrative bodies and law enforcement departments.

The police have sealed the other types of cables in Aokai and taken samples for testing, Yang said.

Established in late 2012, the company was a private firm producing items such as electric cables, control cables and cables for rail transportation.

The company's manufacturing sites have been closed and the account books have been sealed, according to Yang.

The investigation was opened up by the metro company and the city government on March 16, three days after a tip-off was posted online that the company's operations failed to meet industrial standards.

The line was put into use in November and carried 345,000 passengers on the first day of operation.

Contact the writers at zhang_yi@chinadaily.com.cn