A bullet train manufacturer has been suspended from production because of frequent breakdowns on the newly opened Shanghai-Beijing High-speed Railway.

The Changchun Railway Vehicles Co Ltd has made about one-fourth of the trains currently running along the Shanghai-Beijing line that started operation on June 30. The 1,318-kilometer line, China's largest and highest-profile rail project, experienced a troubled start-up with several delays caused by breakdowns.

The Ministry of Railways "was unsatisfied with the frequent breakdown reports" and ordered thorough checks to ensure the operation and safety, the 21 Century Business Herald newspaper reported, quoting unidentified insiders.

China North Locomotive and Rolling Stock Industry (Group) Corporation, the producer's parent company, said the production line did not actually stop but merely "suspended the delivery," according to the report, which quoted Xie Jilong, Secretary of Board with the group.

Xie stressed that it was the company itself that reported the problems to the ministry and is conducting the checks.

Reports said 24 bullet trains of the Shanghai-Beijing rail, which has 96 trains, were produced by the Changchu company. Those trains, model number CRH380BL, saw most of the breakdowns. Nearly 40 breakdowns have been reported since late June, insiders said.

Railway authorities later apologized for the problems, in which passengers were delayed for hours and the power onboard was cut, and explained the line was still in "break-in period."

The line handles an average of 165,000 passengers daily along its 1,318-kilometer-long track, with a peak of 197,000. The on-schedule rate of departure is 94 percent while the rate on arrival is lower at 85.6 percent due the breakdowns, according to the Ministry of Railways.

The manufacturer said the problems along the line did not reflect on the train's safety. Instead, it said the new train-control system is "too sensitive," tending to halt trains very quickly in reaction to any small changes.

"A train has more than 1,000 sensors which respond to various information like speed, temperature and pressure," said the producer.

But the manufacturer admitted the system may sometimes make errors and stop the trains.

The country's expanding railway network is under tight scrutiny after a fatal train crash that killed 40 and injured hundreds of others on July 23 in Wenzhou, Zhejiang Province.

Design flaws in signal equipment and human error caused one of the worst rail accident in China, officials said, and the Ministry of Railways demanded thorough checks on train equipment and maintenance work soon after the crash.

Railway authorities have been saying that it developed the bullet trains on its own and exported high-speed rail to other countries.