Could independent Scotland continue to use pound sterling?

Both sides in the Scottish referendum campaign have held rallies as they make their final efforts to win over undecided voters.

What currency Scotland would use, should it vote "Yes" for independence, has been a key campaign issue.

Alex Salmond has again insisted that Scotland would be able to use the pound whether there was a currency union or not.

However, Westminster party leaders have repeatedly made it clear that this will not happen.

The BBC's economics editor Robert Peston described the situation as an impasse, a situation in which no progress is apparently possible.