A BAD week for Royal Bank of Scotland was rounded off when the taxpayer-backed group was hit by a new computer systems failure and an embarrassing mistake by its number crunchers.

Just 24 hours after the owner of RBS, NatWest and Ulster Bank was fined £56million for a massive computer failure in 2012, the gremlins struck again.

The latest IT glitch affected customers using credit and debit cards but fortunately was resolved within 90 minutes.

And to pile on the woe for chief executive Ross McEwan, RBS admitted it had made an error in its calculations submitted to regulators last month as part of the stress-testing of European banks.

After comfortably passing the test with capital reserves of 6.7 per cent, against a minimum of 5.5 per cent, it turned out it only narrowly made the grade at 5.7 per cent.

McEwan cannot take the blame for historic failures but each new blunder hampers his efforts to restore its reputation.