David Cameron took his message that he was "a patriot for the whole United Kingdom" to a porridge factory in Fife on Thursday, ahead of a meeting with Alex Salmond.
The prime minister toured the Quaker Oats factory in Cupar on the day that it announced a £14.4m investment and 30 new jobs at the site.
Cameron said that businesses regularly question him about investment in Scotland amid the "uncertainty about Scotland's future" created by the independence referendum.
"I've got Cameron blood, and I've got Llewellyn blood. I was born and brought up in England, I'm proud to be English but also proud to be British and I think many people in the UK absolutely feel that you can have all of these identities together, and that is the strength of the UK," he said.
When asked whether a Scottish patriot would prefer the seat of government in their home nation or in another nation, Mr Cameron said: "I think what the Scottish patriot wants is to have decisions made locally in Scotland, for Scotland, but also be part of a larger entity - the United Kingdom."
He added: "That (the UK) gives you enormous influence and reach that makes all of us, not just Scots but English, Northern Irish and Welsh people, stronger, richer, better protected and a fairer country.
"It's all of those things together. You can be a proud Scottish patriot and a proud inhabitant of the United Kingdom."