China's premier Wen Jiabao pledged Thursday to "severely punish" those responsible for a deadly train crash that has sparked public fury and triggered fears over the safety of high-speed rail.

At least 39 people were killed and nearly 200 injured in Saturday's collision on the outskirts of the eastern city of Wenzhou, the worst accident ever to hit China's rapidly expanding high-speed network.

Wen, a popular figure with China's masses, vsited the scene of the crash as the government tries to assuage mounting anger which has dominated the media and the blogosphere in recent days.

"We will severely punish those responsible for the accident and those who hold responsibilities of leadership in accordance with the country's laws," he told reporters at the accident site.

"The high-speed railway construction of China should integrate speed, quality, efficiency and safety. And safety should be put in the first place," said Wen, who has ordered an "open and transparent" probe into the incident.

The accident has raised questions over whether safety concerns may have been overlooked in China's rush to build the world's biggest high-speed rail system, a feat it has achieved in just four years.

China's state-controlled media has been unusually outspoken in its coverage of the accident, defying directives not to question the official line.

A comment piece on the front page of the People's Daily, the Communist party mouthpiece, said Thursday that China "needs development, but does not need blood-smeared GDP."

"Development is of overriding importance. But development should not be pursued at all cost," said the article, which was attributed to "the newspaper's commentator".

"While developing, (we) must... put human safety as the top priority and... balance speed, quality and benefits. We must never solely pursue speed or sacrifice life for money."

Wen, who typically makes highly publicised visits to disaster sites, will meet with the injured as well as relatives of the victims during his trip to Wenzhou, the official Xinhua news agency reported.

He also urged efforts to "make China's high-speed railway exports really safe" -- after observers said that the accident could scuttle Beijing's ambitions to sell the technology overseas.

Officials with the Shanghai Railway Bureau told investigators that "design flaws" in signalling equipment were to blame for Saturday's crash, Xinhua said Thursday, the first public admission that the Chinese-made system was at fault.

The system "failed to turn the green light into red" after being struck by lightning, it quoted Shanghai Railway Bureau head An Lusheng as saying.

Three senior railway officials have already been fired over the disaster, and Beijing has ordered an "urgent overhaul" of national rail safety.

But that has done little to calm the furious response from the public and the media.

Anger has been compounded by allegations that authorities tried to cover up evidence by burying the wreckage, although officials said this was to help rescuers access the crash site.

Thousands of people have posted on China's hugely popular micro-blogs, demanding to know why the driver of the second train, who was killed in the accident, was not told to stop in time.

China has ploughed huge sums of money into its high-speed rail network, which covered 8,358 kilometres (5,193 miles) by the end of 2010 and is expected to exceed 13,000 kilometres by 2012 and 16,000 kilometres by 2020.

A new $33 billion high-speed link between Beijing and Shanghai opened to passengers amid much fanfare on June 30 -- a year ahead of schedule -- but has suffered power cuts and delays.

The high cost of the network has sparked fears over corruption, and China's state auditor has said construction companies and individuals last year siphoned off 187 million yuan ($29 million) from the Beijing-Shanghai project.

The revelation followed the sacking of former railway minister Liu Zhijun in February, who allegedly took more than 800 million yuan in kickbacks over several years on contracts linked to China's high-speed network.

Shortly after his sacking, the railway ministry said trains would run between 250 and 300 kilometres per hour on the new Beijing-Shanghai link, which is designed for a maximum speed of 380 kph, for safety reasons.