The Royal Bank of Scotland's wealth management arm saw a 26% year-on-year rise in operating profit to £240m in the first half of 2009, as net interest income bolstered performance.

The wealth management arm, which includes Coutts, said net interest income grew to £339m from £271m in the first half of 2008. Coutts has one of the biggest mortgage books among UK private banks, which analysts say is behind the rise in interest income.