Don't rip apart UK family in independence vote, British PM David Cameron begs Scotland

British Prime Minister David Cameron implored Scots on Wednesday to shun independence to keep the United Kingdom "family" intact as he scrambled to stem a steep rise in secessionist support ahead of the September 18 vote.

In a sign of panic within the British ruling elite, Cameron and opposition leader Ed Miliband scrapped their weekly question-and-answer session to visit Scotland on Wednesday to ask Scots not to ditch their 307-year union with England.

"We do not want this family of nations to be ripped apart," Cameron, 47, said in an opinion piece published in the Daily Mail newspaper. "The United Kingdom is a precious and special country."

But Cameron tempered the emotion with a clear warning: "If the UK breaks apart, it breaks apart forever."

Cameron has until now been largely absent from the debate after conceding that his privileged background and centre-right politics mean he is not the best person to win over Scots, who are usually more left-wing than the English. But if Scotland votes for independence, Cameron's job will be on the line ahead of a national election planned for May 2015.

Several opinion poll surveys have shown a surge in support for independence over recent weeks, spooking financial markets and raising the biggest internal challenge to the United Kingdom since Irish independence almost a century ago.

Cameron, Miliband and Liberal Democrat Leader Nick Clegg will all visit Scotland on Wednesday in what nationalist leader Alex Salmond said was a sign of panic that could backfire.

"If I thought they were coming by bus I'd send the bus fare," Salmond said. The Scottish leader said Cameron was the most unpopular Conservative leader ever among Scots, and Miliband the most distrusted Labour leader.

Following an independence vote, Britain and Scotland would face 18 months of talks on how to carve up everything from North Sea oil and the pound to European Union membership and Britain's main nuclear submarine base at Faslane.

The formal name for the sovereign state that includes England, Scotland, Wales and Northern Ireland is the United Kingdom of Great Britain and Northern Ireland.

The voluntary union of England, which had subsumed Wales, with Scotland in 1707 created the Kingdom of Great Britain. It became the United Kingdom in 1801 with a formal union with subject Ireland.