Chinese authorities have admitted that a signal failure is responsible for the bullet-train crash that left 39 people dead and nearly 200 injured on Saturday.

A Chinese railway research group -- called The Beijing National Railway Research and Design Institute of Signals and Communications Co. Ltd. -- admitted blame and issued an apology to the people of China.

The crash was China's worst train accident since 2008.

On Saturday night, a high-speed train slammed into another train that was stalled on the track. The stalled train had reportedly lost power when it was struck by lightning, and a signal for the following locomotive failed to change from green to red, giving the second train the "OK" to continue on.

A public outcry has led to some rare public appearances from Chinese officials. The official apology, as well as the press conference from Premier Wen Jiabao on Wednesday to address the issue, came as a surprise to Western commentators,

"No matter if it was a mechanical fault, a management problem, or a manufacturing problem, we must get to the bottom of this," Wen said.

"If corruption was found behind this, we must handle it according to law and will not be soft. Only in this way can we be fair to those who have died."

The railway institute said it will "face up to shouldering responsibility, and accept any punishment that is due, and will strictly undertake pursuing culpability of those responsible", news agency Xinhua reported, citing a statement.

"Safety overrides all else, and high-speed rail safety is of even more overriding importance."

The crash brings  to light questions about the safety of high-speed trains, and may jeopardize China's future in the area. Beijing is currently bidding for a $15 billion rail project in Russia -- indeed, Moscow is already considering giving China a smaller share of the contract.

"Without safety, high-speed trains will lose their credibility," Wen added. "This deadly accident has reminded us to attach more importance to the safety of our high-speed railways."