The FCA has written to investment platforms and SIPP providers to ask them to disclose how much of the interest they receive from cash and bank deposits they pass on to their customers. 

Adviser platform Transact has criticised the approach some other platforms have taken towards cash handling and the use of cash interest.

After years in the doldrums, cash ISA rates are rising rapidly thanks to rapid increases in the bank rate which rose to 4% last week.

The FCA is to push ahead immediately with plans to warn pension savers of the corrosive effect of inflation on cash savings.