Skip Belton, regional council member, issued the stark warning after the announcement of a review of how funds raised regionally are used.
Although the institute bosses, led by Helen Taylor, were merely announcing the need for a review of how cash reserves are used, regional council members were quick to quash any plans for centralising money-spending.
Belton said: 'There would be civil war were the RIBA headquarters to control how money raised by a regional office was spent.'
He was backed by fellow council member Colin James who said: 'It's quite clear - money raised by the region should be used at its discretion.'
The announcement of the review followed an earlier call to devolve powers to the regions and create more autonomy for regional offices.
But the possibility of the RIBA headquarters taking control of how funds are spent flies in the face of the devolution.
In response, Helen Taylor promised to take on board the council members' fears and stated that the review process will be going ahead early next year.