Multi Development, the company behind the scheme, has admitted that 5,500 tonnes of stone sourced from local quarries will be carted by road to Tuscan stonemasons for cutting.
Justifying the decision not to hire UK-based experts, Multi said the Tuscan stonemasons were picked for their 'quality, skill, experience and market competitiveness.'
The stone will be transported on 125 lorries, which Friends of the Earth estimates will spew out 500 tonnes of carbon dioxide.
Wilkinson Eyre's scheme, which includes a much-maligned transport interchange dubbed the 'baked bean tin', includes a flagship department store, along with 58 shops, restaurants and cafés, 93 apartments and a two-level basement car park.
Bath and North East Somerset Council is a strong supporter of Southgate but advocates 'sensible use of vehicles' to reduce carbon emissions.
At the time of going to press the council was unable to comment.