The firm Johnston Carmichael has been appointed to carry out an independent review of the branch and will make a recommendation to RBS on whether the bank should remain open or not.
Mr MacNeil said input from the local community was crucial at this time to keep banking services on Barra.
Speaking after his own interview with the firm, he said: 'I was very heartened after my phone call with Johnston Carmichael. They have the power, frankly, to keep the bank open, and this makes it important that everybody who has a case to keep it open makes sure that case is heard by Johnston Carmichael.
'They will be visiting Barra on Monday August 6 and I would encourage people to get in touch with them to make an appointment or to submit feedback by email or letter.
'The case to keep the Barra branch open is very strong indeed and we also need to resume normal hours at Lochsboisdale, but we need to spell it out for Johnston Carmichael. They have the power to keep the branch open or not and RBS say they will be bound by their decision.
'I would encourage everyone who has an interest, whether large or small – from the point of view of annual crofters' cheques from lamb sales to daily businesses or any charities – to please get involved.
'Your voice is very important at this stage to keep banking services on Barra.'
The review team will be at the RBS branch in Castlebay on Monday August 6. To book an appointment, call 01224 259353.
To give your views to Johnston Carmichael, you can email RBSbranchreview@jcca.co.uk; fill in an online questionnaire at www.jcca.co.uk/rbsbranchreview ; or write to: The RBS Review Team, Johnston Carmichael LLP, 29 Albyn Place, Aberdeen, AB10 1YL.
The deadline for submission of views is 5pm on Tuesday August 14.
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