RBS and Lloyds have drawn up plans to move their banking licences and legal bases to London if the Scottish referendum returns a 'Yes' vote.

Amid uncertainty about the currency that an independent Scotland would use, Lloyds and RBS are concerned that credit ratings agencies would downgrade them if they remained domiciled in Scotland.

Lloyds Banking Group and Royal Bank of Scotland (RBS) want ministers to introduce a new Act of Parliament that would avoid the need for a lengthy legal process handled by the courts.

Directors of both lenders are concerned that the process for moving their banking licences and legal base, using a mechanism called a Part 7 Transfer under the Financial Services and Markets Act, would be too time consuming.

While they have not yet held talks with the Treasury about the details of new legislation, sources close to Lloyds and RBS confirmed on Thursday that they were keen for it to happen.

RBS's relocation would be likely to involve the transfer of some jobs, although it declined to say how many in a statement issued on Thursday morning.

"There are a number of material uncertainties arising from the Scottish referendum vote which could have a bearing on the Bank’s credit ratings, and the fiscal, monetary, legal and regulatory landscape to which it is subject."

"For this reason, RBS has undertaken contingency planning for the possible business implications of a 'Yes' vote," it said.

'No impact on banking services'

RBS insisted that shifting its legal base to England would have "no impact on everyday banking services used by our customers throughout the British Isles".

Underlining the sensitivity of its latest intervention, RBS said that the referendum was "a matter for the Scottish people" and pointed out that it had been based north of the border since 1727.

Lloyds said it was clarifying its own contingency plans following enquiries from customers and employees.

"While the scale of potential change is currently unclear, we have contingency plans in place which include the establishment of new legal entities in England."

"This is a legal procedure and there would be no immediate changes or issues which could affect our business or our customers."

Both banks had already highlighted the potential risks of a 'Yes' vote in results announcements and company documents earlier this year.

The UK Treasury said that such contingency planning was "understandable" but continued to insist that it was not undertaking such work itself.

"The government is not making contingency plans for a yes vote. However, as the Governor of the Bank of England has made clear, the UK authorities are responsible for financial stability in every part of the UK and will do everything necessary to work closely in all circumstances with all financial institutions who are based or wish to be based in the UK."