A late spike in complaints about mis-selling payment protection insurance will wipe out up to a third of Royal Bank of Scotland’s annual profit, the state-owned lender has warned. In an unscheduled update on Wednesday, RBS said the volume of claims received in the run-up to last week’s deadline for complaints was “significantly higher than expected”, and as a result it expects to make a provision of between £600m and £900m in its third-quarter results to account for the costs. RBS was forecast to generate a net profit of £2.7bn this year, according to a company-compiled consensus, meaning that a provision at the top end of the range would be equal to 33.3 per cent of the previous estimate.