The British minister in charge of Scotland has issued a stark warning that the country could sleepwalk into a split from the U.K. because unmotivated unionists are failing to wake up to the threat posed by Scottish First Minister Alex Salmond's nationalists.

Amid clear signs of tension and division in the "no" campaign (against Scottish independence from the United Kingdom), the Scottish secretary (minister for Scotland), Alistair Carmichael, said he believed the nationalists had greater "hunger" for victory and could create an unstoppable momentum.

Carmichael, a Liberal Democrat, said he believed the "yes" campaign (for Scottish independence from the U.K.), which he said was possibly the best financed in British political history, could well move ahead in the polls during the run-up to the Sept. 18 referendum.