The Spitalfields Market Under Threat (SMUT) group has been planning to upset the choreographed opening of the office block at lunchtime on Thursday (6 October).
The campaigners are still furious that the Foster building, designed for the Spitalfields Development Group (SDG), was allowed to go ahead.
'We are amused to read claims by developer SDG that the community was a 'partner' in its completed office development project,' the SMUT statement says.
'Our campaign, as was well known, came directly from the community and had the support of 40,000 signatories to its petition, based on strong feelings about a unique area of London.
'Supporters also include Will Alsop, Terry Farrell, Gilbert and George and Julie Christie.
'And an independent survey of the ward of Spitalfields in 2001 revealed that 90 per cent of residents favoured predominantly community-based uses of the market,' the statement continued.
'The developer's claim that the new office block and windy plaza 'enhance the experience of being in Spitalfields' would be funny if it wasn't so sad,' campaigners said.
The group has also taken the opportunity to breath new life into its campaign to protect the half of the market that was largely unaffected by the development.
'The space inside the remaining half of Spitalfields Market is currently being filled with units for high-rent stores and bars catering to City workers with a resulting loss of independent traders and businesses,' the campaigners warn.