China's bullet trains will continue to go at reduced speeds for some time to allow for further technical inspections, one of the experts investigating the cause of the deadly Wenzhou crash said on Tuesday.

Bullet services to 'stay slow' during checks.[File photo]

China put a go-slow order on high-speed rail services and called for thorough checks on all lines on Aug 16, a move made in response to the fatal accident that claimed 40 lives on July 23.

Although the rate of incidents has fallen sharply since then, Tang Tao, a professor of automation at Beijing Jiaotong University and a member of the crash probe panel, said it is still too early to consider increasing the speed.

"Safety is related to speed, though it's not totally determined by it," he said during a forum in Beijing. "Any technical examination requires an observation period, thus we should let the system cool down before taking further action."

Tang refused to give any details about the investigation report, which was expected in mid-September. However, he said that a lot of accidents in China can come down to "unreasonable project schedules" and could be avoided if more time was allowed for testing.

"I've also learned from the investigation of the (Wenzhou) accident that many workers were actually working 24-7 (to meet deadlines), and multitasking can cause a series of problems," he said.

"We should focus more on the quality of the project, not the launch date," he said, before calling for authorities to re-evaluate the schedules of many projects.

Tang explained that the talent shortage is another challenge constraining the development of bullet trains.

"The average age of technicians on high-speed rail projects is under 40," he said. "They are not given enough time to grow before being assigned major tasks."

Although the professor insisted that railway signal technology in China is world class, he admitted it will still take time for it to be accepted by overseas customers, possibly even longer now because of the Wenzhou tragedy. A failure in signal equipment was one of the suggested causes of the crash after early investigations.