A Chinese bullet train manufacturer said Wednesday it had been told to stop shipments after a series of delays on the new high-speed rail link between Beijing and Shanghai.

China's railway ministry ordered the halt after problems with high-speed trains manufactured by a unit of listed company China CNR Corp, the company said in a statement to the Shanghai Stock Exchange.

The move is the latest blow to Chinese train makers after 40 people died and nearly 200 others were injured in a crash near the eastern city of Wenzhou last month. The incident raised concerns over the safety of the nation's fast-growing high-speed rail sector.

The company said an automatic braking system installed in its trains had caused delays on the high-profile Beijing-Shanghai line, which was built at a cost of $33 billion and opened on June 30.

The trains, which were made by CNR unit Changchun Railway Vehicles Co, were installed with sensors that sent alerts to automatically slow the train down, it said.

Media reports said the system was causing trains to slow or stop unnecessarily.

CNR has uncompleted contracts for the model worth 6.7-billion-yuan ($1.04 billion) and the company said Changchun Railway Vehicle would make efforts to improve the quality of its products.

Chinese media reported a series of delays on the Beijing-Shanghai high-speed line in the weeks after its launch, which was attended by the prime minister and coincided with the Communist Party's 90th anniversary celebrations.

The fatal train crash last month, which involved cars from a different Chinese manufacturer, has been blamed on faulty signalling equipment.

The Shanghai-listed shares of CNR have dropped around 23 percent since the accident.