China's high-speed railways suffered 168 glitches in July, according to a Ministry of Railways report.

The report, issued by the ministry's transport bureau, said 106 of the 168 problems that occurred during the month stemmed from quality problems with the rolling stock, 21st Century Business Herald reported on Friday.

High-speed trains built by China North Locomotive and Rolling Stock Corp Ltd (CNR), one of the nation's two largest train makers, were found to have the most problems. The report said 56 malfunctions occurred in trains manufactured by CNR's Changchun unit and there were 30 problems with the locomotives manufactured by the company's Tangshan unit.

However, the nation's other major bullet train builders, such as a Qingdao unit of China South Locomotive and Rolling Stock Corp (CSR) and the joint venture Bombardier Sifang Power (Qingdao) Transportation Ltd, also had problems with their products.

The report was an internal notice that circulated to local railway authorities and the nation's train makers, urging the companies to conduct a thorough overhaul of their products, the paper reported.

China's fast-expanding high-speed railways have suffered a variety of problems.

Last month CNR recalled 54 high-speed trains used on the Beijing-Shanghai line over safety concerns.

Tan Xiaofeng, a spokesman for the corporation, said the recall of the CRH 380BL trains was due to "small problems with components" and was partly attributable to substandard products provided by suppliers.

But Zhang Lei, an engineer with CNR's Tangshan unit, told 21st Century Business Herald that suspected cracks had been detected in the train axles, which could cause an accident.

However, Wang Jing, a publicity officer at CNR, told China Daily on Sunday the recall had nothing to do with cracks on the axels and none had been found during checks.

On Sunday, the Ministry of Railways said China's railway system has transported approximately 1.27 billion passengers during the first eight months of this year, up 11.8 percent from a year earlier.

The number accounts for 67 percent of a full-year target, according to the ministry's statement on its website.

China's high-speed railways are still recovering from the aftermath of the July 23 Wenzhou tragedy when a high-speed train collided with another that was stalled on a viaduct after a lightning strike in East China's Zhejiang province. Forty passengers died and nearly 200 were injured.

China's high-speed trains have been required to run at slower speeds after a nationwide adjustment of train schedules, effective last month, for safety reasons.