The chief executive of Royal Bank of Scotland, Ross McEwan, has made it clear the bank will adapt its business for an independent Scotland.

Pointing out that RBS has been in Scotland for nearly 300 years, McEwan said: "It's really important that the Scottish people get the opportunity to vote, and then if I need to adapt my business to serve England, Scotland, Wales and both the Republic of Ireland and Northern Ireland, then I will."

His comments came in a Q&A session with readers on the Guardian website. McEwan played down suggestions from the business secretary, Vince Cable, that the bank would relocate its HQ if the Scots vote for independence. "Mr Cable and I have not talked about moving our head office," he said.

His comments come amid claims by SNP deputy first minister, Nicola Sturgeon, that Britain's main political parties are seeking to gang up and bully the people of Scotland to remain in the UK, by threatening to reject a currency union in the event of independence.

In a strong reaction to the Guardian's disclosure that George Osborne, Ed Balls and Danny Alexander are planning to say that an independent Scotland could not keep the pound, the SNP said the three were guilty of "cack-handed panicky" tactics.

McEwan also said RBS would pay bonuses to help retain top bankers, despite analysts expecting the bank to report a loss of up to £8bn for 2013, its sixth successive annual loss.