By Steve Slater
LONDON (Reuters) - Royal Bank of Scotland (RBS)
RBS and the BoE declined to comment.
McEwan had been seen as a leading contender to replace Stephen Hester, who was sacked by the government in June after he said he would not necessarily stay at the bank through the first phase of Britain's sale of its 81 percent stake.
Assuming his selection is approved, his appointment could be announced as early as Thursday or on Friday when RBS reports second-quarter results, the source told Reuters.
McEwan will be tasked with completing RBS's restructuring and ensuring its shares to rise above the government's break-even price so that its stake can be sold. The government values RBS stock at an estimated 407 pence a share on its books.
The New Zealander joined RBS as CEO for UK retail last August from Commonwealth Bank of Australia
By 1100 GMT RBS shares were up 3.7 percent at 329-1/2 pence, helped by strong results from Lloyds
McEwan had run retail banking at Commonwealth Bank for five years, and has worked in the insurance and investment industries in Australia and New Zealand for more than 25 years.
As CEO, he will face intense scrutiny from politicians, the public and the media in one of the highest profile roles in British business.
McEwan told investors and analysts at a presentation in March he had been shocked at how bad UK retail banking was.
"Having come into this market six months ago I've been quite surprised at how bad this industry is from a retail banking perspective. I would even go to say that there's not a good retail bank in the UK and our job is to create that," he said.
(Additional reporting by Abhishek Takle; Editing by Louise Ireland)