Chinese Premier Wen Jiabao has tried to quell rising public anger by visiting the scene of last weekend’s high-speed rail crash and vowing to “severely punish” those responsible for the accident that killed 39 people and has fuelled concerns about the safety of the country’s bullet train system.

In an apparent attempt to narrow the focus of the blame, a railway official pointed the finger at a small research institute in Beijing for designing a signal system with a “severe defect”, and the institute in turn said it would “shoulder the responsibility”.

The tragedy of the crash threatens to turn into a broader crisis of trust for the government, with blogs and normally pliant state media raising questions about China’s rush to build a high-speed rail system as well as its handling of the accident’s aftermath, including the burial of some wreckage before a formal investigation had even begun.