Britain's Prime Minister David Cameron gestures as he delivers a speech at the Aberdeen Exhibition and Conference Centre in Aberdeen, Scotland, September 15, 2014. [Photo/Agencies]

EDINBURGH -- British Prime Minister David Cameron on Monday urged Scots to reject independence and vote No in a last ditch bid to save the Union ahead of Thursday's Scottish independence referendum.

Jetting into Aberdeen in northeast Scotland, Cameron told local Conservative activists that a Yes vote is a decision that means Scots can't go back and "the United Kingdom would be no more".

Scotland and the rest of the Britain "will go our separate ways forever" if there is a Yes vote, he warned, stressing that "There' s no going back from this. No re-run. This is a once-and-for-all decision."

"This is the week that could change the United Kingdom forever," said Cameron, admitting that "many people across Scotland will vote Yes" and "on Friday morning, there may be no more British pensions, passports and pound".

"Scottish independence would not be a trial separation, but a painful divorce," said the British prime minister, stressing "Please don't break up this family of nations" and "Let's stick together".

He emphasized that a No vote is a vote for "concrete change" after the referendum and the change is imminent as "the status quo is gone", pledging major new powers on tax and spending to Scotland.

Cameron dismissed Yes vote as a positive vision, saying that "we want you to stay, from head, heart and soul" and "we are better together".

"No one says you can't be a pride Scot and a pride Briton," he noted, concluding with "please vote to stick together, vote to stay, and vote to save our United Kingdom".

Cameron made the trip after a series of polls at the weekend suggested that the battle for Scotland's future is still too close to call.

Earlier on Monday, Scottish First Minister Alex Salmond appeared at Edinburgh Airport and joined a group of prominent pro- independence business people to hit out at the "scaremongering" of the "No" campaign.

Salmond described the referendum as a "once in a lifetime opportunity for Scotland", insisting that "a positive campaign will always beat the scaremongering campaign".

Last week, a number of financial services firms threatened to head for the exit door if Scotland voted Yes to independence. Deutsche Bank likened a vote for Scotland to leave Britain to the mistakes which led to the Great Depression of the 1930s. Retailers John Lewis and Aldi both warned Scottish shoppers would face higher prices.

According to a survey, 65 percent of 200 of the City of London' s top investors believe Scotland's economy is at risk if it votes Yes.

On Sunday, Queen Elizabeth urged Scots to think "carefully" ahead of Thursday's Scottish independence referendum after attending Church near Balmoral Castle in northern Scotland.

In October 2012, Cameron and Salmond signed the Edinburgh Agreement, allowing Scotland to hold an independence referendum on the question of "Should Scotland be an independent country?"