The forthright call came from Scottish Labour's Margaret Curran, the Shadow Secretary.
She told a Federation of Small Business dinner in Bathgate that something strange was going on - that while many business leaders were more than willing to speak their minds on all manner of policies, when it came to independence, they clammed up.
Her remarks gave vent to a growing frustration among pro-UK forces, within and outwith Whitehall, that while in private, business chiefs express deep concerns about Scottish independence. Yet in public for whatever reason, they stay silent.
Describing next year's referendum as the most important decision that any Scot would face in their life, Ms Curran said the debate needed many voices, and voters expected to hear from the experts, not just from politicians.
"The organisations that make up the fabric of Scotland, that are part of our national life - our charities, our NGOs, our trade unions - can't stay silent and sit on their hands for such an important decision. And that goes for those of you here tonight," she declared.
She reminded business chiefs they told politicians what their needs were in terms of tax, employment regulations and red tape and, when it came to party election manifestos, they pored over the promises in great detail.
"That is right and proper. But something strange has been happening recently.
"Business in Scotland has been uncharacteristically quiet about the referendum. Normally strong-minded business leaders have been silent on the issue of independence."
She said she recently attended a meeting with about 30 senior business leaders who told her precisely what the Government was doing wrong and what Labour should do if it ended up in power again, right down to the rates of tax.
"But when the conversation turned to independence, they told me it was a 'political' matter.
"They wouldn't be commenting and many of them had said they had decided that their position would be to remain neutral.
"Now, I have dealt with business through 14 years of being in elected office and this is unique; that on a decision that has the potential to impact the tax regime, the regulatory environment and the free movement of people, goods and services across borders, business leaders - large and small - sound like they're scared to speak out. In this debate, silence can't be an option."
She claimed the Nationalists wanted silence because it helped their cause.
"So my message to you tonight is this: do not be cowed, do not be intimidated. We want you to interrogate the case for independence in the same forensic way that we have come to expect with budgets and manifestos. No more, no less.
"In 32 days' time when the Scottish Government publish their White Paper - their roadmap for independence - I'm hoping and expecting that I see the same energy and enthusiasm put into responding to it, and scrutinising the proposals, that we are used to from business."
Iain McMillan, director of CBI Scotland, said: "It is true that many business leaders are concerned about independence and a number have spoken out, but others have preferred that the CBI speak for them collectively.
"That is what we have done and will continue to do, although one can understand Mrs Curran's frustrations."