According to the subway construction headquarters in Shanghai, all building foundations should be at least 30 metres from the tunnel and 50 metres from the centre of the stations, but the newspaper said some property developers were ignoring these regulations.

The newspaper claimed that excavation work for a commercial complex near the exit of Xujiahui Station had resulted in ''very serious water leakage'' into the station.

However, the Liberation Daily article was not sourced to any government department or local construction experts and many analysts believe its claims might be exaggerated.

''It is unlikely, given the rigorous planning procedures you have to go through to develop a property in this city, that any building would be allowed to interfere with the subway,'' a Shanghai-based investment consultant said.

An architect pointed out that while placing foundations too close to a subway line or station could cause problems for both the subway and the building, it was not necessarily dangerous.

''Subways are by definition built in crowded urban areas, look at Hong Kong, so it is not as if this is a problem that no one knows about,'' he said.

''Also, you should take into account that a cylindrical tunnel is a very strong structure which can withstand a lot of pressure,'' he added.

The architect said that if there was a problem with construction work near the subway, it was probably because of poor work standards and design faults rather than simply being too close to the subway.

''There could be many different reasons why water is leaking into the Xujiahui station. You cannot definitely say it is the result of the nearby construction work.''