A "radical" restructuring of Royal Bank of Scotland, which is largely owned by the UK taxpayer, could see it transfer control of its Irish operation, Ulster Bank, to the Irish government.

The future of RBS is currently being considered by the Parliamentary Commission on Banking Standards, and a draft report from the commission called for the split of RBS into a good bank and a bad bank.

However, a speculative report from BBC business editor Robert Peston has suggested that "another, more radical option is also being assessed by the Treasury".

This would involve somehow removing Ulster Bank from RBS. The bank has been one of the worst performing parts of the group, with losses of £1 billion in 2012.

Mr Peston said that one idea raised is to "transfer Ulster Bank into the arms and ownership of the Irish government", by swapping all or part of the bank for the British loans and investments currently owned by Ireland's "bad bank", the National Asset Management Agency (Nama).

In a statement, Ulster Bank said: “While we do not comment on speculation, Ulster Bank is a core part of RBS Group and continues to make significant progress.”