SHANGHAI - A SHANGHAI building which collapsed last week, killing a construction worker, did so because contractors had recklessly shifted the earth at its base, the city government said on Friday.

The residential building met design standards but its foundation was undermined as builders piled earth on one side while digging a parking garage on the other side, a top city construction official told a news conference.

'Earth was piled up too high, too quickly,' said Shanghai Urban Construction and Transportation Commission director Huang Rong.

He said the earth was piled as high as 10 metres (33 feet) on one side, while on the other side a 4.6-metre-deep underground garage was under construction.

'The pressure difference from the two sides made the earth move sideways... leading to the collapse of the building,' Mr Huang said at the briefing, held to release the findings of an investigation into the June 27 incident.

As Shanghai undergoes a building boom in preparation for next year's World Expo, the incident has put a spotlight on concerns over quality standards, soaring real estate prices and corruption between developers and officials.

Mr Xie Liming, head of the Shanghai Work Safety Administration, said anyone found responsible for the incident will be prosecuted.

Police put nine people, including the developer and construction company employees, 'under control' this week, meaning they faced restrictions on their movements, a city government spokesman said.

State media have reported the project's developer, Shanghai Meidu Real Estate Company, was owned by several government officials and had been operating illegally since 2004 without a licence.

Hundreds of people who bought apartments in the 11-building complex have demanded refunds. Authorities have frozen the developer's bank account. -- AFP