McEwan also moved to reassure employees that the state-backed lender is well placed to deal with the fallout.
He said: “We had planned extensively for both possible outcomes to ensure we were well placed to support our customers and colleagues.
“The result of the vote carries with it a range of unknowns about the short, medium and long-term prospects for the UK and its economy. Added to this, we now have a period of political uncertainty.”
Shares in RBS, which is 73 per cent owned by the taxpayer, have taken a pummelling since the vote – yesterday falling to their lowest level since the financial crisis, before rebounding today.
New Zealand-born McEwan also gave a nod to the bank’s international workforce, amid fears that Britain could lose access to the single market.
He said: “As someone born outside the UK, I see one of this country’s biggest strengths as its openness to the rest of the world, and the people of it. As a major employer and backer of the economy, we have a duty to ensure that we reflect that.
“The diversity of those who make up this bank at every level is key to our success. In uncertain times I want to ensure that everyone understands that.”
Meanwhile, it emerged today that Britain’s lenders have tapped the Bank of England for another £3.1 billion in extra cash to help bolster their balance sheets following the Brexit vote.
Lenders have now taken more than £9bn from the Bank so far this month after it launched three additional so-called funding auctions surrounding the referendum vote.
It is the first time the Bank has ever held more than one such auction in a month.
Bank governor Mark Carney pledged on Friday to pump at least £250bn into money markets if needed to prevent a credit squeeze.
But the result of the latest funding auction shows little sign of stress in the banking sector and is less than the £3.3bn taken by lenders at the start of the month.
Banks in the UK already have a combined £600bn in liquidity on their balance sheets, helping shield the sector from a repeat of the credit crunch seen at the height of the financial crisis.