The prime minister’s latest intervention will come just a day after he accused the Scottish National Party of threatening Scottish business leaders who questioned the independence argument.

According to the Financial Times, he is expected to tell business leaders and party activists it is time to speak up: “We have heard the noise of the nationalist few, but now it is time for the voices of the silent majority to be heard.”

Cameron – whose previous decision to make pro-union speeches from London attracted derision – will fly to Scotland to make the speech.

Speaking in Parliament on Wednesday, Cameron said he has met Scottish business leader after business leader who describes the switch to independence as “crazy”.

The pro-independence campaign also sports a business arm, the 2,200-strong Business for Scotland.