Britain's Prime Minister David Cameron is pleading with Scots not to vote for independence in the forthcoming referendum in September.

In an emotional speech to be delivered later on 7 February, Cameron argues that an independent Scotland would undermine Britain's image and standing in the world.

"We would be deeply diminished without Scotland," Cameron will say.

"If we lost Scotland, if the UK changed, we would rip the rug from under our own reputation. The plain fact is we matter more in the world together," he will tell an audience at the park used to host London's 2012 Olympic Games.

Scottish people will vote in an independence referendum on 18 September this year and will be asked the straight "yes/no" question: "Should Scotland be an independent country?"

BP's chief executive Bob Dudley has warned this week that major companies may divest billions in future investment away from Scotland because of the uncertainties the country's independence would mean for business.

Dudley said that "all businesses have a concern" about the in/out referendum, which takes place on 18 September 2014.

"It does not seem the right thing to me for the country [Scotland] to drift off. That's not a company view, that's from me," said Dudley.

However, he added that BP would be likely to pay higher costs in the event of Scottish independence and that uncertainty over the country's currency would not help billions of pounds in future investment.

BP was the latest in a line of companies that voiced similar concerns. This includes various investment banks, such as Citi and JPMorgan, and global conglomerates like Unilever.

Meanwhile various coalition and Scottish politicians, as well as the governor of the Bank of England Mark Carney, warned that Scotland may lose the pound and have to reapply to the European Union if it wishes to remain a member in the event of independence.