The new banking tax will complicate National Australia Bank's sale of Clydesdale Bank, says one Australian bank, which has cut its valuation of the UK business by A$425 million (£205m).

Commonwealth Bank of Australia analyst Victor German said the budget changes "appear to be detrimental to NAB's aspirations in listing its UK assets".

CBA said the tax would reduce Clydesdale's full-year 2016 pro forma earnings by about 10 per cent and its full-year 2020 forecast earnings by about 8 per cent.

There was a "further downside risk should these changes result in a permanent de rating of the smaller peer banks in the UK", Mr German said, adding that it might mean NAB would have to sell off a bigger percentage of the UK banks to meet capital targets.