The Prime Minister warned that the Chancellor would reject the possibility of Scotland maintaining the pound post-independence, the Guardian reports.
Speaking at a press conference yesterday he said:
"The chancellor will be discussing this later in the week. I think it would be very difficult to justify a currency union post-independence. But I think it is very important that we set out these arguments in a very clear and rational way."
George Osborne, Danny Alexander and Ed Balls are all reportedly set to rule out Scotland keeping the pound if they become independent after the September vote.
Their comments come after the Bank of England Governor Mark Carney said a currency union for Scotland would involve the loss of some sovereignty.
More top news
More than one in five school staff have had a false allegation made against them by a pupil, according to a survey.
Parents of obese children rarely spot that their child is overweight, doctors warn.
MPs are no longer MPs, just candidates again - Parliament has automatically dissolved and the 'short campaign' begins today.