Royal Bank of Scotland and Lloyds Banking Group, which owns the Bank of Scotland, is to move its headquarters from Edinburgh to London in the event of a Yes vote in the independence referendum.

Lloyds, which also owns Halifax and Scottish Widows, has along with the Royal Bank of Scotland already been involved in discussions with The Treasury over such a move following next week's poll.

RBS is due to confirm its plans in a statement at 7am, before the markets open.

Lloyds said it was announcing the move following a rise in inquiries from customers, its employees and other investors about its plans post-September 19, when the result is due to be announced.

The move will end more than 100 years of heritage for the Edinburgh based Bank of Scotland, which has its head office in St Andrew Square.

Both banks received billions in state aid from Labour at the height of the 2008 financial crisis, when Alistair Darling and Gordon Brown were Chancellor and Prime Minister. Mr Darling leads the Better Together campaign against independence. Mr Brown is playing an increasingly important role in the pro-United Kingdom fightback as the campaign reaches its conclusion.

Lloyds said: "Lloyds Banking Group has seen an increased level of enquiries from our customers, colleagues and other stakeholders about our plans post the Scottish Referendum on Thursday 18th September.

"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.

"There will be a period between the referendum and the implementation of separation, should a 'yes' vote be successful, that we believe is sufficient to take any necessary action."

The group said it would remain committed to its customers on both sides of the Border, regardless of the result.

RBS, which has a sprawling headquarters employing thousands of staff at Gogarburn, to the east of the capital, would not comment on its plans, but it is understood that a statement is due to be made in the early morning.

The Treasury was quick to seize on the Lloyds announcement.

A spokesman said: "Lloyds' contingency plan to relocate to London in the event of a yes vote is understandable. As a general matter, the Government believes any company should be free to choose where to locate its base, in the light of what best suits the stability and competitiveness of its business."

"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."

A Treasury source added: "As you would expect, RBS have also been in touch with us and have similar plans to base themselves in London"