Scotland may be left in a currency limbo if it votes for independence because it is uncertain if it can continue using the pound or immediately join the euro, British lawmakers warned Friday.

Uncertainty over what currency will be used after independence remains a major campaign issue just days before Scots vote in a Sept. 18 referendum whether to leave the United Kingdom after 307 years of union with England.

Britain's three main political parties have ruled out a formal currency union, but Scottish nationalist leader Alex Salmond has said he is confident a deal will be done and that Scotland "cannot be stopped from keeping the pound."