Last week, Sir Bruce publicly criticised plans to give the Scottish Parliament tax-raising powers. Yesterday the Think Twice campaign listed him, along with Sir Donald Mackay, the former chairman of Scottish Enterprise, as a "known sceptic" on devolution.
A Labour Party spokesman said that Sir Bruce must "make his position clear".
"He must make clear whether or not he is in the ranks of Think Twice - or is he prepared to come out openly and say is very angry that the Think Twice campaign has tried to hijack him?" the spokesman asked.
Sir Bruce could only continue to speak on behalf of his bank and other businesses if he did so as an independent figure, he said.
Sir Bruce was not available for immediate comment yesterday, but Brian Monteith, co-ordinator of the Think Twice campaign, said the list had been issued purely as a guide that journalists might find useful.
"He has nothing to do with us," he said. "All we are doing is providing a list of names."Reuse content