Former Canadian prime minister Jean Chretien has questioned the threshold that could allow the Scottish independence referendum to be won by a single vote, and warned the campaign could be emotionally divisive.

Next year's poll will be decided on a formula known as 50% plus one, but Mr Chretien said he had a problem with the thought that he could lose his country if "someone loses their glasses going to vote".

The former PM led Canada during the last referendum on Quebec sovereignty in 1995, when the province voted to stay with Canada by less than 1% of the poll.

Mr Chretien, who was leader of Canada between 1993 and 2003, also warned the independence referendum campaign would be "difficult" and could tear families apart.

The former Liberal leader was speaking as part of a lecture series at the Scotland Office.

Mr Chretien, who is from Quebec and whose native language is French, said: "A referendum is very emotional.

"It is dividing families, dividing cities and villages, especially among those who believe so strongly it is almost a religion.

"You are breaking the dreams of some people.

"And breaking the dream of a kid is tough, but breaking the dream of an adult is more difficult."

He also admitted that his Liberal government had faced a very difficult battle against Quebec nationalists.

He characterised his opposition as portraying independence, not as separation, but as a "new deal" and said: "Who does not want a new deal?"

Although the result was ultimately incredibly close, Mr Chretien said the No campaign had been at 62% in the polls to the Yes campaign's 38% as little as two weeks before the actual referendum day.

He backed the Scottish Government's decision to limit the vote to people living in Scotland.

Mr Chretien said there had been no discussion in Canada about giving a vote to people from Quebec, but who lived outside the province. He added: "All those people would vote no."

Coalition Government sources said they were relaxed about Mr Chretien's comments.

The Canadian also expressed his view that any independence referendum had to be won by a clear majority.

But he praised the wording of the referendum question.

His government passed a Clarity Act following criticism of the convoluted wording of the 1995 question, which ensures any independence can only be won after a clear question.

Asked about the wording for next year's vote "should Scotland be an independent country?" he described it as very clear.