ROYAL Bank of Scotland has repeated its warning of a "material adverse effect" on its business if Scots vote in favour of independence next month.

The Edinburgh-based bank, which is 80 per cent owned by the taxpayer, highlighted the potential for uncertainty caused by a Yes vote, which it said could significantly impact the group's credit ratings as well as the fiscal, monetary, legal and regulatory landscape to which the business is subject.

In a section outlining the risk factors facing the group, RBS said in its half-year results that independence could "significantly impact the group's costs and would have a material adverse effect on the group's business, financial condition, results of operations and prospects".

The comments are in line with a statement made by the bank in its annual report earlier this year. The company, which has maintained a neutral position ahead of the vote, has been holding talks with the Bank of England, UK Financial Investments and the Scottish and UK Governments over the referendum.

The bank's half-year results confirmed figures published last week showing a big jump in operating profits to £2.6bn. It said it has benefited from the improving economy, reduced bad debts and the quicker run down of non-core assets.

Among other Scotland-based financial institutions, Standard Life has said it could move some of its operations if the country votes for independence.

The pensions and savings company - which has been based in Scotland for around 190 years - said earlier this year that it would ''take whatever action we consider necessary'' to give continuity to its customers.

Shares in RBS climbed by as much as 15 per cent on Friday last week after the group released the figures seven days early because they were "significantly stronger" than market expectations.